In plain terms

The claim being assessed: Regular sauna use causally reduces cardiovascular clinical events in adults.

Where the evidence stands: Γ — Plausible mechanism. There is a believable biological story and partial support, but the causal step has not been demonstrated.

What this mechanism does: The evidence reviewed does not show this mechanism causing the outcome. That does not show it has no effect.

Strongest evidence for it: Primary-subclaim aggregation returns SC2 Γ: prospective mortality associations and meaningful controlled physiology/function supply a coherent biological rationale, while same-scope hard-event causal identification remains unverified. This is unconfirmed prevention, not evidence that sauna is physiologically inert or that every heat, cold or neuromodulation intervention is ineffective.

What decisive evidence would look like

In plain terms, researchers would change the proposed cause, confirm it changed as intended, and measure a meaningful health outcome while checking other explanations. The result should be able to support or count against the claim.

Relative explanatory fit: Alternative ranked ahead

What this review means

Sauna changes cardiovascular physiology and may improve selected clinical function, but the evidence does not yet establish that habitual sauna itself prevents hard cardiovascular events across adults.

Implications for health and treatment: Primary-subclaim aggregation returns SC2 Γ: prospective mortality associations and meaningful controlled physiology/function supply a coherent biological rationale, while same-scope hard-event causal identification remains unverified. This is unconfirmed prevention, not evidence that sauna is physiologically inert or that every heat, cold or neuromodulation intervention is ineffective. The 'epiphenomenon' label means a causal role in preventing heart attacks, strokes or cardiovascular deaths is not established by the evidence, not that sauna has no effect: randomized trials show it lowers blood pressure and improves some heart-failure measures.

Limits for individual care: Confidence reflects evidence density and reproducibility: multiple heat/sauna studies with partial replication but heterogeneous comparators, modalities and endpoints; reviewer access depth does not set the band. The grade applies to the exact registered claim; stronger findings for narrower subclaims remain separate. No complete-paper audit or blinded calibration is claimed. This educational review does not establish an individual treatment recommendation.

Medical information notice: This review provides general health information, not medical advice. It cannot diagnose a condition or replace an individual discussion with a qualified clinician.

Source checking used bounded original primary abstract passages/status records and selected original partial-body passages. No complete-abstract or complete-paper audit, or independent scientific peer review, is claimed. Detailed access counts and limitations appear in the review.

A low grade is not an accusation. It means the causal work has not been done yet, which is the ordinary state of most actively studied mechanisms in biology.

At a glance

Sub-claims assessed separately

Full assessment

From here the review is written for a technical reader: caps and thresholds, competing models, the independence basis, and the citation ledger.

Sources: 59 primary reports; claims: 65; verified: 65; unverified: 0. Verification is bounded attribution. Access: 3 partial-body and 56 bounded abstract/status examinations. Literature cutoff: 2026-10-13; source examination UTC date: 2026-10-13. No complete-paper audit or blinded calibration claimed. Adversarial review: Generated by Sol 6.1; adversarially reviewed by Claude Opus 5.5 (Anthropic) on 2026-10-14 (3 corrections applied) and again on 2026-11-02 (9 findings; corrections applied). See ADVERSARIAL REVIEW AND APPROVAL. Status: Approved as revised.

AT A GLANCE

Sauna changes cardiovascular physiology and may improve selected clinical function, but the evidence does not yet establish that habitual sauna itself prevents hard cardiovascular events across adults.

Deciding experiment: A multicenter randomized pragmatic sauna-plus-usual-care versus matched usual-care/time-contact study, or a validated independent access/withdrawal natural experiment, with adjudicated cardiovascular hospitalization, infarction, stroke and cardiovascular death over prespecified follow-up, stratifying baseline disease and exercise before outcomes.

Belief versus evidence: Primary-subclaim aggregation returns SC2 Γ: prospective mortality associations and meaningful controlled physiology/function supply a coherent biological rationale, while same-scope hard-event causal identification remains unverified. This is unconfirmed prevention, not evidence that sauna is physiologically inert or that every heat, cold or neuromodulation intervention is ineffective.

Best-supported rival: Controlled physiological and restricted functional benefit. Randomized exercise-plus-sauna35785965 shows that heat can add measured blood-pressure and estimated-fitness effects beyond exercise allocation, and the CKD crossover42113470 shows acute vascular and walking gains. Neither tests hard cardiovascular events, so they identify scoped physiological benefit, not sauna event prevention.

COMPETING MECHANISTIC MODELS

Rank 1: Controlled physiological and restricted functional benefit (Ε). Repeated or acute heat improves selected physiological or functional outcomes in defined settings while hard-event prevention remains unconfirmed. Exercise-plus-sauna35785965 has a genuine BP/estimated-fitness positive and acute CKD42113470 improves measured walking; Waon27001189 has selected secondary function positives. The WAON primary BNP contrast is null, the CAD37650138 vascular/BP trial is null and modalities/cointerventions differ; this is not general event prevention.

Rank 2: Cold and vagal interventions have separate mechanisms and indications (Ε). Out-of-scope companion; not evidence for or against the registered sauna claim. Exact interventions can help some outcomes and fail or hinder others without being interchangeable with sauna. TREAT-AF32192678 shows a named home-device objective arrhythmia benefit; cold25121612 helps selected acute submaximal work. Cold training26174323 can attenuate adaptation, and cervical-diabetes38546822 fails symptoms; neither cold nor all-device equivalence is established.

Rank 3: Repeated heat changes cardiovascular disease trajectory (Γ). Habitual sauna causally lowers hard cardiovascular events through thermal/autonomic/vascular effects. Finnish event gradients25705824/30486813 align with controlled thermal physiological evidence and selected restricted function. Matched severe-HF Waon prognosis19304125 adds a genuine five-year composite-event association. Self-selection and overlapping cohort family remain; randomized trials do not yet establish the registered hard-event causal effect and some mechanisms are context-null.

Rank 4: Healthy-user and fitness differences (Β). Health, fitness, social circumstances and reverse selection explain some apparent longevity association. Measured fitness and sauna jointly associate with lower mortality28972808, and higher-use groups differ in health/lifestyle; residual confounding remains plausible. Controlled exercise-plus-sauna benefits35785965 cannot be dismissed as baseline healthy-user selection, although they do not settle the event association.

The tournament does not alter the nominal level. Compatible pathways and flexible alternatives are not automatically proved by explaining observations.

FULL REVIEW

Registered claim and scope

Regular sauna use causally reduces cardiovascular clinical events in adults.

The precise lead clinical proposition is SC2. Mechanism, competing-cause, generalization and safety companions remain separately reported; they do not replace the primary clinical endpoint.

Selection: position 14 in the registered editorial traffic-priority list; registration timestamp 2026-10-13T16:06:25.313824+00:00. Ranked editorial traffic priority rather than measured global popularity or a preset verdict. Registered claim assessed against original sources; no independent blinded calibration is claimed.

Evidence and causal interpretation

Rubric fit: No dedicated cardiovascular-prevention rubric ships in frozen v5.3. Rubric06 is adapted explicitly to a positive controlled hard cardiovascular event/trajectory endpoint for SC2; lifespan/healthspan language and universal caps remain unchanged. SC1 intermediate responses are reported as verified physiology rather than treated as event mediation. Cold recovery and medical neuromodulation have separate endpoints; rubric07 is additionally routed to SC5 for active-sham, expectancy, blinding and device-specific inference, with objective AF burden distinguished from subjective wellness. SC4, SC5, the Rank 2 rival and the rubric07 routing concern cold-water immersion, cold showers and vagus-nerve devices, which are outside the registered sauna claim; they are retained as out-of-scope companions and are not evidence for or against it.

The largest sauna event findings come from Finnish prospective observational data, particularly the KIHD cohort family. Dose and duration gradients and measured fitness are informative. They do not remove self-selection, unmeasured social/health differences or exposure change over decades, and later reanalyses of overlapping men cannot be treated as new independent causal lines. The older men-and-women cohort expands enrollment without making the entire evidence base geographically independent. Incident stroke shows the same inverse gradient in the KIHD men-and-women sample (1628 adults, 155 strokes; HR 0.38, 95% CI 0.18-0.81, for 4-7 versus 1 session per week after physical-activity and socioeconomic adjustment; PMID 29720543, ref 58), which adds a non-mortality endpoint but not an independent cohort. An independent Japanese prospective cohort of 30,076 adults found near-daily hot-tub bathing associated with lower incident cardiovascular disease (HR 0.72, 0.62-0.84) and stroke, but not with sudden cardiac death (PMID 32209614, ref 59); it is a different heat modality and is observational, so it bears on geographic replication of the association, not on causation.

Randomized studies establish a meaningful thermal stimulus, with context-dependent benefits and nulls. The exercise-plus-sauna trial has a positive systolic-pressure and estimated-fitness contrast over exercise alone. Original Methods show fitness was estimated from a submaximal heart-rate test and most participants were women; it is not a directly measured gas-exchange fitness result or an event-prevention experiment.

Supervised Waon in established heart failure differs from ordinary Finnish sauna exposure. WAON-CHF specifies a primary BNP endpoint whose between-group change did not reach significance, although selected secondary function measures improved. The smaller Holter trial reduced premature ventricular contractions but did not demonstrate fewer sudden deaths. The CAD trial achieved acclimation without better vascular/BP endpoints. These findings must not be collapsed into a uniformly positive clinical prevention result. The separately examined five-year prognosis original PMID19304125 reports 31.3% versus 68.7% HF/cardiac-death composite events in 64 Waon recipients versus 65 matched traditional-care controls. This is a genuine hard-event association in severe established HF, not merely a surrogate report. Random allocation is not stated, and eight versus twelve deaths do not by themselves establish an isolated mortality effect or general primary-prevention benefit.

Cold claims require separate testing. Cold immersion can improve some acute submaximal recovery or pain scores while repeated cooling can impair training adaptation. A recent placebo-controlled soccer study found no added recovery/adaptation benefit. The cold-shower trial randomized 3018 participants but was unblinded and self-reported; sickness absence improved while overall illness days did not. Retrospective registration and unverified compliance limit causal interpretation of immune or durable-health claims.

Vagus-nerve devices likewise cannot be assessed as one product. TREAT-AF used a named Parasym device at home with a specified active tragus versus stimulated-earlobe comparator and objective ECG-patch outcomes. It supplies real auricular clinical trial evidence, contradicting a blanket dismissal of all consumer-style devices. Defined cervical-diabetes and stroke trials nevertheless have primary nulls. Symptoms, biomarkers, objective arrhythmia burden and implanted-device equivalence are distinct propositions.

Consensus was useful for organizing cohort overlap, modality differences and gaps, but source checking corrects its overreach. Review-mediated Waon BNP ranges cannot override the original primary-null WAON-CHF contrast. Nonsignificant illness-day findings are not zero change, and absence cells in a provider matrix do not demonstrate absent literature. Strong numerical sauna-harm claims from a review are not carried without a verified original and relevant exposure scope.

The original cold-shower correction PMID30071104 was examined on the publisher site: it adds a missing Supporting Information dataset underlying Table 2. It is attached to its parent and does not add an original-study row or establish a revised endpoint; the supplementary data were not audited. The lupus correction is attached at metadata depth only.

HYPOTHESIS STATE EVALUATION FRAMEWORK (HSEF v5.3)

Subclaim matrix and aggregation

Preregistered aggregation: primary-subclaim. Primary-subclaim aggregation returns SC2 Γ: prospective mortality associations and meaningful controlled physiology/function supply a coherent biological rationale, while same-scope hard-event causal identification remains unverified. This is unconfirmed prevention, not evidence that sauna is physiologically inert or that every heat, cold or neuromodulation intervention is ineffective. Sensitivities: weakest-link Β; primary-subclaim Γ; scope-matched Γ.

Decisive-perturbation inventory and causal tally

[7] A randomized thirty-person heart-failure trial reduced Holter premature-ventricular-contraction counts and improved selected HRV/BNP measures after repeated supervised infrared sauna. Ectopy burden is a rhythm endpoint, not demonstrated fewer sudden deaths or major clinical events; small unequal arms and short follow-up limit broad prevention claims.

[8] A nine-person supervised sauna crossover reported tolerability but no significant between-group exercise-endurance or heart-failure-questionnaire benefit; only one neuroendocrine contrast was significant. Pilot size yields imprecise nulls and does not establish equivalence or safety for all heart-failure patients or temperatures.

[9] The 149-person multicenter WAON-CHF randomized trial found selected secondary NYHA/walking/cardiothoracic improvements, but the primary between-group BNP change was not significant. Primary-negative short inpatient adjunct therapy cannot be presented as an event-prevention success or transferred to unsupervised Finnish sauna.

[16] A twenty-two-person PAD randomized comparison of heat-plus-calisthenics and supervised exercise found walking/BP improvements in both arms without significant between-arm functional differences. No nonexercise control and different cointervention doses prevent attributing benefit solely to heat; hot-water therapy is not sauna and no event reduction was tested.

[17] A ten-person CKD randomized crossover found greater vascular responses and six-minute walking distance after a single infrared-sauna exposure than thermoneutral control. Acute pilot function and reassuring short kidney markers do not establish sustained benefit or reduced cardiovascular events.

[18] Hot-water versus thermoneutral crossover in thirteen adults with diabetes increased thermal strain but did not improve insulin sensitivity, FMD or selected cardiometabolic markers acutely. The single exposure and another heat modality constrain chronic sauna inference; null markers do not prove all heat benefits absent.

[20] Six-week randomized local heating/sham/exercise comparison improved selected resistance-artery measures with heating but not exercise power; exercise improved power and angiogenesis. Vascular proxy benefits are not functional-training equivalence or hard-event prevention, and local heating differs from sauna.

[25] The forty-seven-analyzed-participant randomized exercise-plus-sauna arm had lower systolic BP/cholesterol and higher estimated cardiorespiratory fitness than exercise alone after eight weeks. Fitness was estimated from a submaximal heart-rate test rather than directly measured maximal oxygen uptake; predominantly female sample, bundle exposure and no events limit prevention transfer.

[28] An eight-week forty-one-person randomized Finnish-sauna CAD trial achieved heat acclimation without improved FMD, arterial stiffness or blood pressure; reactive-hyperemia contrasts did not support benefit. A genuine disease-context null constrains mechanism generalization, but it does not directly test mortality or prove no possible prevention benefit.

[31] A twelve-week randomized strength-training comparison found smaller strength/mass gains with repeated cold-water recovery than active recovery, with separate acute mechanistic findings. Male training-specific harm does not prove all cold use harmful; it directly challenges equating acute recovery or hormetic stress with durable training benefit.

[32] Randomized soccer-player cold/hot-water versus sham-laser recovery showed no superiority in acute performance recovery or fifteen-week adaptation. Young male athletes and small longer-term completer sample do not establish equivalence or all-population health outcomes.

[40] The 3018-person unblinded cold-shower trial reduced self-reported sickness absence by 29 percent but not overall illness days; original Methods confirm self-report and retrospective registration before analysis. Work attendance is not fewer infections or cardiovascular benefit; no sauna comparison, blinding or verified adherence establishes durable comparable health effects, and the linked correction adds omitted underlying Table 2 data without an asserted endpoint revision.

[47] The 53-person TREAT-AF trial used a named home Parasym device with tragus versus earlobe stimulation and blinded outcome assessors; ECG-patch AF burden was lower at six months. This is a genuine specific-device/indication positive, not proof every consumer stimulation reproduces implanted benefits or prevents stroke/death; intermittent ECG windows and small sample remain.

[52] A thirty-six-person blinded stroke-thrombectomy trial did not change its primary 24-hour systolic-pressure-variability outcome despite molecular/HRV changes. Safety/feasibility and gene effects are not success on the primary endpoint or proof of a durable neurological/device benefit.

[54] A 145-randomized-person multicenter cervical-stimulation diabetes trial found no greater gastrointestinal symptom reduction than sham over either period. A defined null constrains broad device/mechanism transfer but does not negate successes in different indications; gastric-emptying change did not establish symptom benefit.

[57] In 129 NYHA III/IV heart-failure patients, 64 supervised Waon recipients and 65 age/gender/NYHA-matched traditional-care controls had five-year HF or cardiac-death composite rates 31.3% versus 68.7%; deaths were eight versus twelve. No random allocation stated; matched advanced-HF adjunct treatment with continued postdischarge exposure is not habitual sauna primary prevention. Selection, co-care and composite components remain unresolved; deaths alone do not establish isolated mortality reduction.

Tally: 0 positive qualifying study units across scoped subclaims; 27 screened discriminating contrast units. These are not independent causal lines or proof of full-claim necessity/sufficiency. Null and negative contrasts are discriminators, not positive threshold crossings. Reports and replications are not independent causal lines. No same-scope positive hard-event causal study unit is claimed for the broad sauna prevention proposition. Secondary functional positives and actual ECG arrhythmia-burden positives are important but do not become sauna mortality-prevention trials. Sham labels, objective assessors and allocation-guess verification are separate facts. No universal assertion of zero effect or complete absence of thermal event reports is made.

No positive field-valid crossing was verified for the registered causal scope in this bounded audit. Pivotal null or negative tests remain informative; their implications depend on comparator quality, target engagement, power and the registered scope.

Cap audit, precedence and Β/Γ/Δ boundary

A controlled thermal experiment can establish an intermediate or restricted functional effect in its actual setting. Universal biomarker and association constraints govern its transfer to fewer cardiovascular events. Multiple overlapping event-cohort reports are not independent causal lines, and actual device-specific clinical benefits are preserved without licensing a device-class equivalence inference. No weak leg is re-capped over a verified same-scope complementary causal set; such an event-prevention set was not verified.

Universal six-cap audit: All six universal caps were considered: cell-only inference, unperturbed association, ectopic expression, biomarker-only intervention, forced transfer/seeding, and inherited-to-sporadic scope transfer. Each binds its offered inference; complementary same-scope causal classes are assessed together rather than re-capped in isolation.

Gamma hard-rule audit: Controlled BP/FMD, oxidative stress, HRV and acclimation cannot substitute for hard events. Cold subjective/work-absence outcomes do not establish fewer illness days or sauna-equivalent prevention. Named clinical VNS positives remain device/indication scoped rather than dismissed or generalized.

SC1 cap: “Biomarker change without functional/phenotypic change caps at Γ.” Controlled human heat studies establish real physiological responses. Their Γ assignment here concerns the prevention-mechanism inference: blood pressure, flow, thermal acclimation and other intermediate changes are not proof of fewer hard cardiovascular events. Positive walking/function studies retain their specific clinical context; the physiological phenomenon itself is not denied.

SC2 cap: boundary-check ceiling “No field-valid hard-event perturbation: ceiling Γ”, with universal cap 2, “Pure association evidence — however large, however replicated — cannot exceed Β.”, binding the KIHD event evidence (an association leg) at Β. The Finnish event cohorts show persuasive prospective inverse associations, and a matched 129-patient severe-heart-failure Waon cohort reports fewer five-year HF/cardiac-death composite events. Neither source establishes random allocation or an independent causal instrument; supervised adjunct therapy is also distinct from habitual sauna primary prevention. Randomized thermal trials address short-term risk factors, ectopy or function with meaningful positive and null results. No independently valid same-scope sauna hard-event causal experiment was verified; Γ captures mechanism/partial intervention support.

SC3 cap: “Pure association evidence — however large, however replicated — cannot exceed Β.” Measured fitness and socioeconomic adjustment reduce selected explanations but do not eliminate unmeasured healthy-user, prior-disease, social and exposure-selection effects. A joint-association analysis of overlapping participants is not an independent instrument; confounding independence remains unestablished at Β.

SC1 field-valid definition: “ - Genetic or pharmacologic intervention producing reproducible lifespan/healthspan extension - Must separate developmental effects from true aging effects - Biomarker change alone does NOT satisfy this threshold” Positive full-scope result: no. Controlled human heat studies establish real physiological responses. Their Γ assignment here concerns the prevention-mechanism inference: blood pressure, flow, thermal acclimation and other intermediate changes are not proof of fewer hard cardiovascular events. Positive walking/function studies retain their specific clinical context; the physiological phenomenon itself is not denied.

SC2 field-valid definition: “ - Genetic or pharmacologic intervention producing reproducible lifespan/healthspan extension - Must separate developmental effects from true aging effects - Biomarker change alone does NOT satisfy this threshold” Positive full-scope result: no. The Finnish event cohorts show persuasive prospective inverse associations, and a matched 129-patient severe-heart-failure Waon cohort reports fewer five-year HF/cardiac-death composite events. Neither source establishes random allocation or an independent causal instrument; supervised adjunct therapy is also distinct from habitual sauna primary prevention. Randomized thermal trials address short-term risk factors, ectopy or function with meaningful positive and null results. No independently valid same-scope sauna hard-event causal experiment was verified; Γ captures mechanism/partial intervention support.

SC3 field-valid definition: “ - Genetic or pharmacologic intervention producing reproducible lifespan/healthspan extension - Must separate developmental effects from true aging effects - Biomarker change alone does NOT satisfy this threshold” Positive full-scope result: no. Measured fitness and socioeconomic adjustment reduce selected explanations but do not eliminate unmeasured healthy-user, prior-disease, social and exposure-selection effects. A joint-association analysis of overlapping participants is not an independent instrument; confounding independence remains unestablished at Β.

SC4 field-valid definition: “ - Genetic or pharmacologic intervention producing reproducible lifespan/healthspan extension - Must separate developmental effects from true aging effects - Biomarker change alone does NOT satisfy this threshold” Positive full-scope result: no. Cold has specific acute performance/symptom results and an unblinded self-reported sickness-absence positive, alongside training-adaptation harm and placebo-null findings. None establishes durable cardiovascular or overall health benefit comparable with sauna. Γ retains partial intervention support without extrapolating absence from nonsignificance.

SC5 field-valid definition: “at least one of: - Active comparator matched for acute subjective effect, blinding integrity measured and reported - Blinded on/off, staggered-onset, or randomized-withdrawal neuromodulation, reversible and within-subject - Mediator manipulation with the intervention intact: antagonist blockade of the acute experience with the drug still given, or dosing under general anaesthesia - Depletion or challenge experiment in humans whose outcome is symptom trajectory, not a biomarker - Psychotherapy component dismantling, or scaffold removal from a drug arm, with blinded assessors

Rating-scale or biomarker change alone does NOT satisfy this threshold when the claim is functional, and statistical mediation alone never satisfies it.” Positive full-scope result: no. Defined noninvasive devices can have genuine clinical effects, including home Parasym stimulation with objective AF-burden benefit. That disproves a blanket claim that auricular devices have no controlled evidence. Yet exact product, site, current, indication and comparator cannot be transferred across all consumer products or equated with implanted medical stimulation; the broad equivalence inference remains Γ.

SC1 applied rubric adaptation (distinct from the unchanged literal criterion): Document controlled physiological target effects; the unchanged biomarker cap governs transfer to clinical-event prevention, not the existence of thermal hemodynamic responses.

SC2 applied rubric adaptation (distinct from the unchanged literal criterion): A hard cardiovascular event or clinically meaningful disease trajectory is the clinical healthspan analogue. Valid natural experiments and independent exposure/withdrawal instruments can qualify; an RCT is not the only route.

SC3 applied rubric adaptation (distinct from the unchanged literal criterion): Fitness/social adjustment is a measured-confounding check, not random exposure allocation or an independent causal instrument.

SC4 applied rubric adaptation (distinct from the unchanged literal criterion): Durable health, acute symptom recovery and adaptation outcomes are distinct; cold exposure must be evaluated by its own modality and comparator.

SC5 applied rubric adaptation (distinct from the unchanged literal criterion): Use objective disease-specific outcomes and credible sensory-matched sham to assess named noninvasive devices. Universal consumer-to-implanted equivalence requires direct matched product/indication evidence; biomarker correlation does not establish vagal mediation.

SC1 literal Γ hard rule: “ROS change measurements alone” Triggered for oxidative-stress support offered alone as prevention; these markers do not establish hard-event causality.

SC1 literal Γ hard rule: “NAD level change measurements alone” No qualifying NAD-based prevention claim is used.

SC1 literal Γ hard rule: “Mitochondrial metrics alone” Not a qualifying prevention crossing; muscle mitochondrial markers are intermediate physiological evidence.

SC1 literal Γ hard rule: “Senescence marker changes alone” No senescence-only prevention evidence is used.

SC1 literal Γ hard rule: “Single-species or single-strain evidence” Not triggered: every source that sets a subclaim level is a human study; the only animal component, TO-2 cardiomyopathic-hamster oxidative-stress experiments within ref 6 (PMID 21173495), is mechanistic context and sets no level.

SC1 literal Γ hard rule: “Biomarker-only improvement without organismal benefit” Triggered for isolated BP/FMD/BNP/HRV/stress-marker support when offered as fewer hard cardiovascular events; specific observed function/arrhythmia outcomes retain their own endpoint scope.

SC2 literal Γ hard rule: “ROS change measurements alone” Triggered for oxidative-stress support offered alone as prevention; these markers do not establish hard-event causality.

SC2 literal Γ hard rule: “NAD level change measurements alone” No qualifying NAD-based prevention claim is used.

SC2 literal Γ hard rule: “Mitochondrial metrics alone” Not a qualifying prevention crossing; muscle mitochondrial markers are intermediate physiological evidence.

SC2 literal Γ hard rule: “Senescence marker changes alone” No senescence-only prevention evidence is used.

SC2 literal Γ hard rule: “Single-species or single-strain evidence” Not triggered: every source that sets a subclaim level is a human study; the only animal component, TO-2 cardiomyopathic-hamster oxidative-stress experiments within ref 6 (PMID 21173495), is mechanistic context and sets no level.

SC2 literal Γ hard rule: “Biomarker-only improvement without organismal benefit” Triggered for isolated BP/FMD/BNP/HRV/stress-marker support when offered as fewer hard cardiovascular events; specific observed function/arrhythmia outcomes retain their own endpoint scope.

SC3 literal Γ hard rule: “ROS change measurements alone” Triggered for oxidative-stress support offered alone as prevention; these markers do not establish hard-event causality.

SC3 literal Γ hard rule: “NAD level change measurements alone” No qualifying NAD-based prevention claim is used.

SC3 literal Γ hard rule: “Mitochondrial metrics alone” Not a qualifying prevention crossing; muscle mitochondrial markers are intermediate physiological evidence.

SC3 literal Γ hard rule: “Senescence marker changes alone” No senescence-only prevention evidence is used.

SC3 literal Γ hard rule: “Single-species or single-strain evidence” Not triggered: every source that sets a subclaim level is a human study; the only animal component, TO-2 cardiomyopathic-hamster oxidative-stress experiments within ref 6 (PMID 21173495), is mechanistic context and sets no level.

SC3 literal Γ hard rule: “Biomarker-only improvement without organismal benefit” Triggered for isolated BP/FMD/BNP/HRV/stress-marker support when offered as fewer hard cardiovascular events; specific observed function/arrhythmia outcomes retain their own endpoint scope.

SC4 literal Γ hard rule: “ROS change measurements alone” Triggered for oxidative-stress support offered alone as prevention; these markers do not establish hard-event causality.

SC4 literal Γ hard rule: “NAD level change measurements alone” No qualifying NAD-based prevention claim is used.

SC4 literal Γ hard rule: “Mitochondrial metrics alone” Not a qualifying prevention crossing; muscle mitochondrial markers are intermediate physiological evidence.

SC4 literal Γ hard rule: “Senescence marker changes alone” No senescence-only prevention evidence is used.

SC4 literal Γ hard rule: “Single-species or single-strain evidence” Not triggered: every source that sets a subclaim level is a human study; the only animal component, TO-2 cardiomyopathic-hamster oxidative-stress experiments within ref 6 (PMID 21173495), is mechanistic context and sets no level.

SC4 literal Γ hard rule: “Biomarker-only improvement without organismal benefit” Triggered for isolated BP/FMD/BNP/HRV/stress-marker support when offered as fewer hard cardiovascular events; specific observed function/arrhythmia outcomes retain their own endpoint scope.

SC5 literal Γ hard rule: “Functional-unblinding rule. Inert-placebo trial of an intervention with unmistakable acute subjective effects — psychedelics, ketamine, entactogens, suprathreshold stimulation, ECT — with no blinding-integrity check reported. Such a trial did not control what it claims to control.” Not triggered literally for this assembled scoped case. Any adapted clinical, proxy or system-inference restriction is stated separately in the subclaim rationale.

SC5 literal Γ hard rule: “Mediation-by-correlation rule. Candidate mediator correlated with outcome, never manipulated.” Not triggered literally for this assembled scoped case. Any adapted clinical, proxy or system-inference restriction is stated separately in the subclaim rationale.

SC5 literal Γ hard rule: “Open-label rule. Open-label, single-arm, retrospective, or naturalistic evidence alone. A positive open-label result never crosses Δ, however large.” Applies to the uncontrolled or cell-only positive support class, with ceiling Γ; it does not upgrade that class or describe the whole source set.

SC5 literal Γ hard rule: “Unblinded-rater rule. Outcomes rated by clinicians who delivered the intervention or knew allocation.” Not triggered literally for this assembled scoped case. Any adapted clinical, proxy or system-inference restriction is stated separately in the subclaim rationale.

SC5 literal Γ hard rule: “Acute-pharmacodynamic rule. Acute molecular, occupancy, or imaging change with no link to symptom trajectory.” Not triggered literally for this assembled scoped case. Any adapted clinical, proxy or system-inference restriction is stated separately in the subclaim rationale.

SC5 literal Γ hard rule: “Rodent-proxy rule. Forced-swim, tail-suspension, sucrose-preference, or head-twitch alone; head-twitch is pharmacodynamic, not therapeutic.” Not triggered literally for this assembled scoped case. Any adapted clinical, proxy or system-inference restriction is stated separately in the subclaim rationale.

Upward threshold ladder

SC1 Δ: “Requires at least one intervention changing lifespan or healthspan in a way consistent with the hypothesis.” Satisfied: no. A registered exposure-specific clinical experiment or independent natural instrument with relevant endpoints, credible comparator, prespecified modality/dose, baseline disease, adequate follow-up and safety. For SC2 this requires hard cardiovascular events; cold and consumer-device equivalence require their own durable/head-to-head outcome tests.

SC2 Δ: “Requires at least one intervention changing lifespan or healthspan in a way consistent with the hypothesis.” Satisfied: no. A registered exposure-specific clinical experiment or independent natural instrument with relevant endpoints, credible comparator, prespecified modality/dose, baseline disease, adequate follow-up and safety. For SC2 this requires hard cardiovascular events; cold and consumer-device equivalence require their own durable/head-to-head outcome tests.

SC3 Δ: “Requires at least one intervention changing lifespan or healthspan in a way consistent with the hypothesis.” Satisfied: no. A registered exposure-specific clinical experiment or independent natural instrument with relevant endpoints, credible comparator, prespecified modality/dose, baseline disease, adequate follow-up and safety. For SC2 this requires hard cardiovascular events; cold and consumer-device equivalence require their own durable/head-to-head outcome tests.

SC4 Δ: “Requires at least one intervention changing lifespan or healthspan in a way consistent with the hypothesis.” Satisfied: no. A registered exposure-specific clinical experiment or independent natural instrument with relevant endpoints, credible comparator, prespecified modality/dose, baseline disease, adequate follow-up and safety. For SC2 this requires hard cardiovascular events; cold and consumer-device equivalence require their own durable/head-to-head outcome tests.

SC5 Δ: “Requires a controlled human interventional study with a credible active comparator, or a mediator manipulation in humans, with a pre-registered primary outcome.” Satisfied: no. A registered exposure-specific clinical experiment or independent natural instrument with relevant endpoints, credible comparator, prespecified modality/dose, baseline disease, adequate follow-up and safety. For SC2 this requires hard cardiovascular events; cold and consumer-device equivalence require their own durable/head-to-head outcome tests.

Upper ladder: Dose-response event cohorts, measured-fitness contrasts, thermal randomization, physiological manipulation and withdrawal observations were examined. Natural exposure/withdrawal and hard-event perturbation are valid alternatives to an RCT. Overlapping Finnish cohorts share selection and confounding structures, while restricted function/physiology and subjective cold outcomes are not independent causal confirmation of fewer sauna cardiovascular events.

Independence: No nominal or companion reaches Ζ. Different papers from KIHD, different surrogate assays, and repeated device studies of one modality are not independent causal classes merely because titles, sites or sponsors differ. Exact models are reported without transferring their causal scope.

Falsification and pitfalls

Confirmation by biomarker. BP, FMD, BNP, oxidative markers, HRV or thermal acclimation are treated as proof of event prevention.

Replication confused with reproduction. KIHD reanalyses and secondary device-trial cytokine reports are counted as independent studies.

Selective generalization. Supervised infrared Waon, hot-water exercise bundles and localized heating are transferred to all sauna use; specific clinical devices to all consumer products.

Negative field-valid perturbation read as a crossed threshold. WAON primary BNP, CAD vascular/BP, cold-placebo and cervical-diabetes nulls are not positive causal crossings.

Missing-control interpretation. Within-group significance and absent sauna-only or passive control arms are treated as between-group causal proof.

Mechanism conflation. Heat, cold and electrical vagal stimulation are bundled as interchangeable stress or wellness interventions.

Adversarial steelman: above, then below

One rung above (Δ): the exposure-dose and duration gradients for hard events are prospective, measured-fitness adjustment does not erase them, and controlled heat studies provide intervention support for plausible cardiovascular pathways. A valid natural experiment or independently corroborated exposure/withdrawal event analysis could legitimately cross Δ without an RCT.

One rung below (Β): actual hard-event sauna evidence is primarily observational, with shared recruitment and self-selection. If only the clinical endpoint were considered, a conservative reviewer could hold the nominal to association.

Δ is rejected because independent hard-event causal allocation/instruments or sufficiently distinct same-scope causal lines were not verified; controlled biomarkers/function cannot be assumed to mediate mortality. Β is rejected for SC2 because its own scope contains randomized human thermal interventions with disease-relevant functional and rhythm endpoints in heart failure (WAON-CHF secondary NYHA and 6MWD; Holter PVC reduction) and a matched, non-randomized Waon cohort with fewer hard events; these exceed co-occurrence, but none is a field-valid hard-event perturbation, so Γ holds. The full claim therefore remains Γ while the hard-event association is separately described as observational. The severe-HF matched hard-event positive19304125 is retained in this balance; its lack of stated random allocation and treatment/indication mismatch prevent an automatic causal crossing for habitual sauna in adults.

Final score, causal direction and M/S/D

Primary-subclaim aggregation returns SC2 Γ: prospective mortality associations and meaningful controlled physiology/function supply a coherent biological rationale, while same-scope hard-event causal identification remains unverified. This is unconfirmed prevention, not evidence that sauna is physiologically inert or that every heat, cold or neuromodulation intervention is ineffective.

For the registered hard cardiovascular event reduction, no causal dependency of habitual sauna was directly established in either direction. The framework role is an evidence-state classification for this endpoint, not proof sauna is biologically inactive; experimentally demonstrated thermal physiology and specific clinical benefits are reported separately. Here 'epiphenomenon' means only that a causal role for habitual sauna in preventing hard cardiovascular events is not established by the evidence; it does not mean sauna has no effect, since randomized trials show it causally lowers blood pressure (PMID 35785965) and reduces ventricular ectopy in heart failure (PMID 15564698).

Momentum: Mechanistic only. Verified randomized work includes CAD37650138, exercise-plus-sauna35785965 and acute CKD42113470; HFpEF41831305 describes a larger controlled trial as being planned. No verified active hard-event sauna trial or independent event natural experiment was identified, so planned work is not mislabeled underway.

Stability: Stable. A named hard-event causal experiment would move the grade, but none was verified as pending; planned HFpEF functional work does not automatically determine the broad prevention letter.

Divergence: Contested. No manufactured field consensus or arithmetic gap. These dimensions do not change level or confidence.

PROPOSED DECISIVE EXPERIMENTS

A multicenter randomized pragmatic sauna-plus-usual-care versus matched usual-care/time-contact study, or a validated independent access/withdrawal natural experiment, with adjudicated cardiovascular hospitalization, infarction, stroke and cardiovascular death over prespecified follow-up, stratifying baseline disease and exercise before outcomes.

Readout: Adjudicated hard-event incidence and clinically meaningful function; BP/FMD/BNP and autonomic markers secondary, with mechanism mediation separately tested rather than assumed. Controls: Repeated measured exposure/adherence, balanced exercise and clinical care, contact/relaxation comparator, blinded outcome adjudication, prespecified high-risk/primary-prevention strata and complete adverse-event capture; natural experiments require explicit exclusion and selection checks. Supporting: A reproducible clinically important event reduction survives independent causal design and exposure/health confounding checks; restricted phenotypic effects explain a verified portion of the event difference. Falsifying: Adequately precise unchanged event rates despite exposure/target engagement, or event differences explained by selection/co-care; a biomarker-positive event-null result does not cross the prevention threshold.

KNOWLEDGE GAPS

Independent clinical-event causal evidence for habitual sauna, with repeated exposure and settings beyond the Finnish cohort family; the one independent non-Finnish cohort found concerns hot-water bathing, not sauna.

Whether BP/vascular/autonomic changes mediate events rather than simply coexist with exposure.

Sauna-alone versus exercise-plus-sauna and modality equivalence without substituting water immersion, infrared Waon or local heating.

Durable cold-health endpoints and indication-specific recovery/adaptation tradeoffs, with measured expectancy and adherence.

Exact consumer-device identity and indication-specific active-sham evidence; implanted, cervical and auricular stimulation cannot be interchanged by label.

Longer-term benefit-harm data in predefined disease and medication strata without converting supervised short tolerability into universal safety.

REVIEWER NOTES

Fifty-nine original abstracts/status records (57 at the 2026-10-13 cutoff; two added on 2026-11-02 under adversarial finding S5) and selected Methods/Results were actually examined and receipted. No complete-paper/supplement audit, exhaustive systematic search, blinded calibration, independent scientific peer review or rendered video is claimed. Provider counts and downloads are not primary examination credit.

Search leads, reviews, protocols and correction notices do not pad the primary count. Downloaded XML does not earn examination credit. Linked notices remain attached; unexamined correction details limit inference. This is a coordinator source/claim consistency assessment, not independent blinded calibration.

Consensus and original-source reconciliation

Consensus accurately reports the 2315-men cohort, 190 sudden deaths, 407 fatal cardiovascular events and the adjusted frequent-use SCD association. These are prospective observed events, not randomized sauna prevention. Reference groups are predominantly different sauna frequencies, rather than a representative no-sauna population; repeated papers cannot multiply independent exposure allocation. Original PMID25705824.

Consensus correctly highlights measured fitness and cohort overlap. The original joint-analysis associations strengthen a confounder-specific check but reuse the KIHD male cohort family. Baseline gas-analyzed fitness and statistical adjustment do not make sauna exposure randomized or eliminate every health/social selection process. Original PMID28972808.

Consensus summarizes review-mediated BNP decreases and function gains without visibly retaining the requested original trial primary-null distinction. The original 149-person randomized report designates pre/post BNP ratio as primary; its between-group BNP change did not reach significance while selected NYHA/6MWD/cardiothoracic secondary outcomes improved. Primary and secondary results remain separately reported, and no broad event prevention follows. Original PMID27001189.

Consensus correctly identifies an eight-week added-sauna systolic-pressure and fitness estimate over exercise alone. Original Methods show 48 enrolled/47 analyzed, most participants women, and estimated VO2max from a submaximal heart-rate test. Thus the real positive is retained, with estimated rather than directly gas-measured fitness and no hard-event endpoint. Original PMID35785965.

Consensus accurately notes the 41-person CAD randomized null for FMD, stiffness and BP despite acclimation. The result constrains vascular mechanism generalization; it does not directly demonstrate zero mortality benefit. A separate review-mediated 93 percent ischemia claim was not verified against an original and is excluded from our numeric evidence cards. Original PMID37650138.

Consensus describes reduced absence despite zero change in actual illness days. Original Methods establish unblinded self-reported outcomes and unverified compliance; Results report no significant overall illness-day group effect, rather than exact zero or objective infection surveillance. Sickness absence IRR 0.71 is retained. The examined original correction adds omitted underlying Table 2 data, not a revised outcome or retraction. Original PMID27631616.

Consensus notes attenuated resistance adaptation after cold recovery. The original reports a 21-man twelve-week training experiment and a separate nine-man acute biopsy experiment. Smaller strength/mass gains with repeated cold are a genuine training-context boundary; a separate acute submaximal recovery positive25121612 is not discarded or converted into durable health. Original PMID26174323.

Consensus categorically contrasts validated clinical cervical/implanted paths with consumer auricular devices lacking comparable sham-controlled evidence. Original TREAT-AF Methods name a home Parasym device, stimulated tragus versus stimulated earlobe, blinded outcome assessors and ECG-patch AF-burden primary measurement. Its 53-person positive contradicts a blanket no-evidence assertion for every auricular/home device, while not establishing all-brand or implanted-equivalence claims. Original PMID32192678.

Consensus coverage cells report no vagal literature in several domains; such retrieval gaps are not literature absence. The original multicenter cervical-diabetes trial had no active-sham gastrointestinal symptom superiority, and cytokine-null39251831 is a secondary NCT04143269 analysis. Defined negative and positive trials should coexist rather than be generalized by device label. Original PMID38546822.

Consensus cites a review-mediated 38% reduction in cardiac events over five years. The verified original reports HF/cardiac-death composite rates 68.7% in 65 matched traditional-care controls versus 31.3% in 64 Waon recipients: a 37.4 percentage-point difference, not an unambiguously stated 38% relative reduction. The study reports matching, without stated random allocation, in NYHA III/IV heart failure; deaths were twelve versus eight. We retain this clinically important event association without treating it as a mortality-prevention RCT or ordinary-sauna primary prevention. Original PMID19304125.

Consensus was used to identify literature and cross-check specific claims about design, endpoints, scope and research gaps. Those aspects were checked against original primary abstracts/status records and selected original Methods/Results passages. Consensus output was not treated as original full text. Provider search omissions are not evidence that a study does not exist. Source access and examination receipts are retained. Scite use or monthly unavailability is recorded per case; provider citation counts do not change causal grades.

Research timeline and gaps: Sauna and Cardiovascular Prevention

Selected publication milestones, not an exhaustive history or discovery priority claim.

2003 — Small controlled warm/cold hydrotherapy bundle has selected heart-failure symptom/function effects without isolating modalities. Original PMID14564334.

2004 — Supervised sauna reduces measured ectopy in a small heart-failure trial; hard-event reduction remains a different outcome. Original PMID15564698.

2008 — Multicenter Waon report adds short-term disease-specific cardiac and symptom data, with many within-arm contrasts. Original PMID18922381.

2009 — Small supervised sauna crossover is tolerated but lacks significant between-arm function/QoL efficacy. Original PMID19154844.

2009 — Matched severe-heart-failure Waon follow-up reports a five-year HF/cardiac-death composite association; allocation and primary-prevention scope remain unresolved. Original PMID19304125.

2012 — Acute sauna/exercise hypertension comparisons address short-term hemodynamics. Original PMID22863164.

2015 — Finnish male cohort links baseline sauna frequency/duration with fatal events prospectively. Original PMID25705824.

2015 — Chronic cold recovery attenuates selected strength adaptation despite acute recovery rationale. Original PMID26174323.

2016 — WAON-CHF primary BNP is null while selected secondary functional measures improve. Original PMID27001189.

2016 — Unblinded cold showers reduce self-reported absence rather than overall illness days. Original PMID27631616.

2018 — KIHD fitness/sauna joint analysis narrows measured confounding without creating independent exposure allocation. Original PMID28972808.

2018 — Older men-and-women Finnish cohort expands observational enrollment and adds fatal-event associations. Original PMID30486813.

2019 — PAD heat-plus-calisthenics versus exercise comparison shows functional improvement without clear between-arm superiority. Original PMID31002283.

2020 — Named home auricular device with active sensory comparator reduces objective AF burden in a defined disease trial. Original PMID32192678.

2022 — Exercise-plus-sauna randomized trial adds BP and estimated-fitness benefits over exercise. Original PMID35785965.

2023 — CAD randomized exposure achieves acclimation without the predicted vascular/BP benefit. Original PMID37650138.

2024 — Defined cervical-stimulation diabetes trial is clinically symptom-null despite broader vagal-treatment hypotheses. Original PMID38546822.

2024 — Specific sham-controlled auricular insomnia trial has clinically meaningful symptom effects. Original PMID39680406.

2025 — Cold/hot athlete recovery does not exceed placebo in measured acute and longer-term performance outcomes. Original PMID40498100.

2025 — Added hot-water exposure improves selected vascular/BP measures beyond exercise but not all cardiometabolic endpoints. Original PMID40719540.

2025 — Hyperacute-stroke device trial changes molecular/autonomic measures without its primary BP-variability benefit. Original PMID41455014.

2026 — Open HFpEF sauna pilot shows function gains and partial loss after withdrawal, with a controlled trial described as planned. Original PMID41831305.

2026 — Acute CKD controlled sauna pilot shows selected function and vascular positives with limited horizon. Original PMID42113470.

Research gaps

Independent clinical-event causal evidence for habitual sauna, with repeated exposure and settings beyond the Finnish cohort family; the one independent non-Finnish cohort found concerns hot-water bathing, not sauna.

Whether BP/vascular/autonomic changes mediate events rather than simply coexist with exposure.

Sauna-alone versus exercise-plus-sauna and modality equivalence without substituting water immersion, infrared Waon or local heating.

Durable cold-health endpoints and indication-specific recovery/adaptation tradeoffs, with measured expectancy and adherence.

Exact consumer-device identity and indication-specific active-sham evidence; implanted, cervical and auricular stimulation cannot be interchanged by label.

Longer-term benefit-harm data in predefined disease and medication strata without converting supervised short tolerability into universal safety.

Boundary experiment

A multicenter randomized pragmatic sauna-plus-usual-care versus matched usual-care/time-contact study, or a validated independent access/withdrawal natural experiment, with adjudicated cardiovascular hospitalization, infarction, stroke and cardiovascular death over prespecified follow-up, stratifying baseline disease and exercise before outcomes.

ADVERSARIAL REVIEW AND APPROVAL

Authoring model: Sol 6.1. Adversarial reviewer: Claude Opus 5.5 (Anthropic). Date: 2026-10-14.

Scope of checks. All 57 REFERENCES PMIDs verified against PubMed get_article_metadata (57/57 resolve to the stated title, first author, journal and year within the ±1 print/e-pub convention; no retractions or expressions of concern). Fourteen load-bearing claims spot-checked against original abstracts, and the locally held partial-body text for PMID 35785965 was re-read against the review's Methods assertions. Scoring logic checked: cap precedence, the pre-registered aggregation rule and its reported alternatives, the Β/Γ/Δ boundary, the Ζ independence basis, the confidence band text, the role-of-mechanism derivation and the Momentum artifact requirement. Validator re-run.

Rejected findings (checked, no change).

1. Reference years. Thirteen references print the issue year where PubMed carries an e-pub year one apart (refs 4, 6, 12, 20, 23, 28, 29, 33, 35, 37, 42, 48, 49). Within the stated ±1 convention.
2. Reference 12 title. PubMed renders "cerebrovascular-CO2" without the subscript; the review's form is correct, not an error.
3. "Best-supported rival" renderer bug. Checked competing_models.models_evaluated: entry 0 has rank_in_tournament: 1 and is_nominal: false; the nominal is entry 2 (rank 3). The prose names the genuine rank-1 rival, so no fix needed.
4. Scope-matched aggregation. The declared rule is primary-subclaim (SC2), applied as written; the reported scope-matched sensitivity (Γ) is also correct — SC2 is the only subclaim whose scope matches the registered adult hard-event claim, and the Ε-level rivals are tournament models, not subclaims. Weakest-link Β matches the lowest subclaim (SC3). No change.
5. Momentum boilerplate. "Mechanistic only" is used, not "Decisive work underway", and the judgement names its artifacts (PMIDs 37650138, 35785965, 42113470, with 41831305 recorded as planned). Correct as written.
6. Collective-author and empty-DOI defects. None present; every reference carries a named first author and a resolving DOI.
7. Reviewer-notes provenance. The REVIEWER NOTES make no claim that Consensus work was absent, and the case holds its own Consensus reconciliation section with examination receipts; no false-approval or false-provenance clause is present. No earlier adversarial approval is asserted for this case, and none was invented.
8. Headline level and confidence. Γ with "Mechanistically plausible, partial system support" is the canonical descriptor; counts (57 sources, 63 claims, 63 verified, 0 unverified) agree between the banner, scorecard provenance_header and verification_summary. Role epiphenomenon follows step 2 of the derivation procedure for the registered hard-event endpoint. Retained.
9. Load-bearing numbers. PMID 19304125 (129 patients; 64 vs 65; 31.3% vs 68.7%; 8 vs 12 deaths), 27001189 (76+73 = 149; BNP-ratio primary not significant), 27631616 (3018 randomized; IRR 0.71; illness days null), 32192678 (26+27 = 53; AF burden lower at 6 months), 38546822 (68+77 = 145 randomized; symptom null both periods), 25705824 (2315 men; 190 SCD, 407 fatal CVD), 28972808 (2277 men; gas-analysed fitness), 30486813 (1688 participants), 15564698 (30 patients, 20 vs 10), 35785965 (48 enrolled / 47 analysed, 42 of 48 female, estimated V̇O2max from a YMCA-type submaximal bicycle test) all verified against source. No misattribution found.

Residual limitations. Verification remains bounded attribution: 54 of 57 sources were examined at abstract/status depth, so claims resting on unexamined full-text detail (e.g. compliance verification in PMID 27631616, the retrospective-registration assertion) carry the review's own stated access caveat. The adversarial pass did not re-run a literature search and so cannot certify completeness of the source set at the 2026-10-13 cutoff.

Approval: Following adversarial review and the corrections listed above, the revised document is approved. — Claude Opus 5.5 (Anthropic), 2026-10-14.

Second adversarial pass (2026-11-02)

Authoring model: Sol 6.1 (run in Codex). Adversarial reviewer: Claude Opus 5.5 (Anthropic). Date: 2026-11-02. Full log: ADVERSARIAL_REVIEW.sauna-cardiovascular-prevention.md and adversarial-findings.sauna-cardiovascular-prevention.json.

Level Γ and confidence Moderate are unchanged on re-derivation. Corrections applied on 2026-11-02:

• S1 (Major, scope). The "Best-supported rival" box no longer cites the out-of-scope TREAT-AF device trial; SC4, SC5 and the Rank 2 rival are marked as out-of-scope companions; the rubric07 routing and references 31-56 are labelled as outside the registered claim (no reference deleted); the confidence rationale counts only in-scope heat/sauna reports.
• S2 (Major, causal-role gloss). The role category stays "epiphenomenon" (the frozen framework vocabulary has five values); a clarifying sentence now states that the label means a causal role in hard-event prevention is not established by the evidence, not that sauna has no effect.
• S3 (Minor). SC1 restated as "Sauna-induced physiological changes mediate a reduction in cardiovascular events." so the statement matches its Γ rationale.
• S4 (Minor). SC2 cap now cites the boundary-check ceiling with universal cap 2 binding the KIHD association evidence at Β; the Β-rejection sentence now rests on SC2's own evidence.
• S5 (Minor). Added the KIHD incident-stroke report (ref 58, PMID 29720543) and an independent Japanese hot-tub bathing cohort (ref 59, PMID 32209614), both verified in PubMed on 2026-11-02; knowledge gap 1 amended. Level unchanged.
• S6 (Minor). Template "hamster" text in the single-species hard-rule lines replaced. The adversarial log's proposed wording ("no animal-model source is in the inventory") was amended because ref 6 (PMID 21173495) contains a TO-2 cardiomyopathic-hamster component; that component sets no level.
• S7 (Minor). Reader-summary confidence wording aligned with the score card; access depth is not a confidence criterion.
• S8 (Editorial). Score-card reviewer reconciled to Sol 6.1 (run in Codex).
• S9 (Editorial). Numeral/acronym spacing corrected in the score card's Consensus cross-check text; the public CONSENSUS_CROSSCHECK files are regenerated by the site build.

Approval: Following the second adversarial review and the corrections listed above, the revised document is approved. — Claude Opus 5.5 (Anthropic), 2026-11-02.

REFERENCES

References 31-56 (cold-water immersion, cold showers and vagus-nerve stimulation) support only the out-of-scope companion subclaims SC4 and SC5 and the Rank 2 rival; they are retained for transparency and are not evidence for or against the registered sauna claim. References 58 and 59 were added on 2026-11-02 (adversarial finding S5); numbering of references 1-57 is unchanged.

1. Laukkanen T, Khan H, Zaccardi F et al. Association between sauna bathing and fatal cardiovascular and all-cause mortality events. JAMA internal medicine. 2015. PMID 25705824. DOI: 10.1001/jamainternmed.2014.8187. Access: abstract_metadata. Study: KIHD-original-men.

2. Laukkanen JA, Jae SY, Kauhanen J et al. The Interplay between Systolic Blood Pressure, Sauna Bathing, and Cardiovascular Mortality in Middle-Aged and Older Finnish Men: A Cohort Study. The journal of nutrition, health & aging. 2023. PMID 37248758. DOI: 10.1007/s12603-023-1895-1. Access: abstract_metadata. Study: KIHD-original-men.

3. Laukkanen T, Kunutsor SK, Khan H et al. Sauna bathing is associated with reduced cardiovascular mortality and improves risk prediction in men and women: a prospective cohort study. BMC medicine. 2018. PMID 30486813. DOI: 10.1186/s12916-018-1198-0. Access: abstract_metadata. Study: KIHD-later-older-men-and-women.

4. Kunutsor SK, Khan H, Laukkanen T et al. Joint associations of sauna bathing and cardiorespiratory fitness on cardiovascular and all-cause mortality risk: a long-term prospective cohort study. Annals of medicine. 2018. PMID 28972808. DOI: 10.1080/07853890.2017.1387927. Access: abstract_metadata. Study: KIHD-original-men.

5. Kominami K, Noda K, Takahashi N et al. Cardiovascular reactions for whole-body thermal therapy with a hot pack and Waon therapy. International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group. 2020. PMID 32046537. DOI: 10.1080/02656736.2020.1723719. Access: abstract_metadata. Study: PMID32046537.

6. Fujita S, Ikeda Y, Miyata M et al. Effect of Waon therapy on oxidative stress in chronic heart failure. Circulation journal : official journal of the Japanese Circulation Society. 2011. PMID 21173495. DOI: 10.1253/circj.cj-10-0630. Access: abstract_metadata. Study: PMID21173495.

7. Kihara T, Biro S, Ikeda Y et al. Effects of repeated sauna treatment on ventricular arrhythmias in patients with chronic heart failure. Circulation journal : official journal of the Japanese Circulation Society. 2004. PMID 15564698. DOI: 10.1253/circj.68.1146. Access: abstract_metadata. Study: PMID15564698.

8. Basford JR, Oh JK, Allison TG et al. Safety, acceptance, and physiologic effects of sauna bathing in people with chronic heart failure: a pilot report. Archives of physical medicine and rehabilitation. 2009. PMID 19154844. DOI: 10.1016/j.apmr.2008.06.029. Access: abstract_metadata. Study: PMID19154844.

9. Tei C, Imamura T, Kinugawa K et al. Waon Therapy for Managing Chronic Heart Failure　- Results From a Multicenter Prospective Randomized WAON-CHF Study. Circulation journal : official journal of the Japanese Circulation Society. 2016. PMID 27001189. DOI: 10.1253/circj.CJ-16-0051. Access: abstract_metadata. Study: PMID27001189.

10. Miyata M, Kihara T, Kubozono T et al. Beneficial effects of Waon therapy on patients with chronic heart failure: results of a prospective multicenter study. Journal of cardiology. 2008. PMID 18922381. DOI: 10.1016/j.jjcc.2008.07.009. Access: abstract_metadata. Study: PMID18922381.

11. Michalsen A, Lüdtke R, Bühring M et al. Thermal hydrotherapy improves quality of life and hemodynamic function in patients with chronic heart failure. American heart journal. 2003. PMID 14564334. DOI: 10.1016/S0002-8703(03)00314-4. Access: abstract_metadata. Study: PMID14564334.

12. Skinner BD, Lucas RAI, Lucas SJE. Exposure to passive heat and cold stress differentially modulates cerebrovascular-CO2 responsiveness. Journal of applied physiology (Bethesda, Md. : 1985). 2024. PMID 37969086. DOI: 10.1152/japplphysiol.00494.2023. Access: abstract_metadata. Study: PMID37969086.

13. Ross EZ, Cotter JD, Wilson L et al. Cerebrovascular and corticomotor function during progressive passive hyperthermia in humans. Journal of applied physiology (Bethesda, Md. : 1985). 2012. PMID 22134692. DOI: 10.1152/japplphysiol.00988.2011. Access: abstract_metadata. Study: PMID22134692.

14. Hyldahl RD, Hafen PS, Nelson WB et al. Passive muscle heating attenuates the decline in vascular function caused by limb disuse. The Journal of physiology. 2021. PMID 34487346. DOI: 10.1113/JP281900. Access: abstract_metadata. Study: PMID34487346.

15. Jimenez C, Koulmann N, Mischler I et al. Plasma compartment filling after exercise or heat exposure. Medicine and science in sports and exercise. 2002. PMID 12370564. DOI: 10.1097/00005768-200210000-00014. Access: abstract_metadata. Study: PMID12370564.

16. Akerman AP, Thomas KN, van Rij AM et al. Heat therapy vs. supervised exercise therapy for peripheral arterial disease: a 12-wk randomized, controlled trial. American journal of physiology. Heart and circulatory physiology. 2019. PMID 31002283. DOI: 10.1152/ajpheart.00151.2019. Access: abstract_metadata. Study: PMID31002283.

17. Chavez DA, Garten RS, Rodriguez-Miguelez P et al. Acute effects of passive heat exposure on vascular function and exercise capacity in patients with chronic kidney disease. American journal of physiology. Heart and circulatory physiology. 2026. PMID 42113470. DOI: 10.1152/ajpheart.00020.2026. Access: abstract_metadata. Study: PMID42113470.

18. Behzadi P, Ravanelli N, Gravel H et al. Acute effect of passive heat exposure on markers of cardiometabolic function in adults with type 2 diabetes mellitus. Journal of applied physiology (Bethesda, Md. : 1985). 2022. PMID 35323077. DOI: 10.1152/japplphysiol.00800.2021. Access: abstract_metadata. Study: PMID35323077.

19. Cheng JL, Pizzola CA, Mattook KC et al. Acute vascular function responses predict chronic vascular function changes to heating and exercise interventions in young, healthy recreationally active adults. American journal of physiology. Heart and circulatory physiology. 2025. PMID 41171178. DOI: 10.1152/ajpheart.00721.2025. Access: abstract_metadata. Study: PMID41171178.

20. Kaluhiokalani JP, Wallace TE, Ahmadi M et al. Six weeks of localized passive heat therapy elicits some exercise-like improvements in resistance artery function. The Journal of physiology. 2025. PMID 39004886. DOI: 10.1113/JP286567. Access: abstract_metadata. Study: PMID39004886.

21. Hesketh K, Shepherd SO, Strauss JA et al. Passive heat therapy in sedentary humans increases skeletal muscle capillarization and eNOS content but not mitochondrial density or GLUT4 content. American journal of physiology. Heart and circulatory physiology. 2019. PMID 31074654. DOI: 10.1152/ajpheart.00816.2018. Access: abstract_metadata. Study: PMID31074654.

22. Steward CJ, Hill M, Menzies C et al. Post-exercise hot water immersion enhances haemodynamic and vascular benefits of exercise without further improving cardiorespiratory fitness, glucose, lipids or inflammation. The Journal of physiology. 2025. PMID 40719540. DOI: 10.1113/JP288873. Access: abstract_metadata. Study: PMID40719540.

23. Thomas KN, van Rij AM, Lucas SJ et al. Lower-limb hot-water immersion acutely induces beneficial hemodynamic and cardiovascular responses in peripheral arterial disease and healthy, elderly controls. American journal of physiology. Regulatory, integrative and comparative physiology. 2017. PMID 28003211. DOI: 10.1152/ajpregu.00404.2016. Access: abstract_metadata. Study: PMID28003211.

24. Wigati KW, Locatelli JC, Costa JG et al. Comparison between exercise and hot water immersion on skin microvascular responses in older adults with overweight and obesity. European journal of applied physiology. 2026. PMID 42803957. DOI: 10.1007/s00421-026-06415-2. Access: abstract_metadata. Study: PMID42803957.

25. Lee E, Kolunsarka I, Kostensalo J et al. Effects of regular sauna bathing in conjunction with exercise on cardiovascular function: a multi-arm, randomized controlled trial. American journal of physiology. Regulatory, integrative and comparative physiology. 2022. PMID 35785965. DOI: 10.1152/ajpregu.00076.2022. Access: full_text_partial. Study: PMID35785965.

26. Bekfani T, Abo Hwach A, Moebert R et al. Effects of Sauna bathing on Exercise Capacity and Muscle Function in HFpEF. European journal of heart failure. 2026. PMID 41831305. DOI: 10.1093/ejhf/xuag082. Access: abstract_metadata. Study: PMID41831305.

27. Francisco MA, Colbert C, Larson EA et al. Hemodynamics of post-exercise vs. post hot water immersion recovery. Journal of applied physiology (Bethesda, Md. : 1985). 2021. PMID 33630675. DOI: 10.1152/japplphysiol.00260.2020. Access: abstract_metadata. Study: PMID33630675.

28. Debray A, Gravel H, Garceau L et al. Finnish sauna bathing and vascular health of adults with coronary artery disease: a randomized controlled trial. Journal of applied physiology (Bethesda, Md. : 1985). 2023. PMID 37650138. DOI: 10.1152/japplphysiol.00322.2023. Access: abstract_metadata. Study: PMID37650138.

29. Hussain JN, Cohen MM, Mantri N et al. Infrared sauna as exercise-mimetic? Physiological responses to infrared sauna vs exercise in healthy women: A randomized controlled crossover trial. Complementary therapies in medicine. 2022. PMID 34954348. DOI: 10.1016/j.ctim.2021.102798. Access: abstract_metadata. Study: PMID34954348.

30. Gayda M, Paillard F, Sosner P et al. Effects of sauna alone and postexercise sauna baths on blood pressure and hemodynamic variables in patients with untreated hypertension. Journal of clinical hypertension (Greenwich, Conn.). 2012. PMID 22863164. DOI: 10.1111/j.1751-7176.2012.00637.x. Access: abstract_metadata. Study: PMID22863164.

31. Roberts LA, Raastad T, Markworth JF et al. Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training. The Journal of physiology. 2015. PMID 26174323. DOI: 10.1113/JP270570. Access: abstract_metadata. Study: PMID26174323.

32. Gustafsson J, Montiel-Rojas D, Romare MGA et al. Cold- and hot-water immersion are not more effective than placebo for the recovery of physical performance and training adaptations in national level soccer players. European journal of applied physiology. 2025. PMID 40498100. DOI: 10.1007/s00421-025-05835-w. Access: abstract_metadata. Study: PMID40498100.

33. Horgan BG, West NP, Tee N et al. Effect of repeated post-resistance exercise cold or hot water immersion on in-season inflammatory responses in academy rugby players: a randomised controlled cross-over design. European journal of applied physiology. 2024. PMID 38613679. DOI: 10.1007/s00421-024-05424-3. Access: abstract_metadata. Study: PMID38613679.

34. Fröhlich M, Faude O, Klein M et al. Strength training adaptations after cold-water immersion. Journal of strength and conditioning research. 2014. PMID 24552795. DOI: 10.1519/JSC.0000000000000434. Access: abstract_metadata. Study: PMID24552795.

35. Poppendieck W, Wegmann M, Hecksteden A et al. Does Cold-Water Immersion After Strength Training Attenuate Training Adaptation? International journal of sports physiology and performance. 2021. PMID 33217726. DOI: 10.1123/ijspp.2019-0965. Access: abstract_metadata. Study: PMID33217726.

36. Yamane M, Ohnishi N, Matsumoto T. Does Regular Post-exercise Cold Application Attenuate Trained Muscle Adaptation? International journal of sports medicine. 2015. PMID 25760154. DOI: 10.1055/s-0034-1398652. Access: abstract_metadata. Study: PMID25760154.

37. Roberts LA, Nosaka K, Coombes JS et al. Cold water immersion enhances recovery of submaximal muscle function after resistance exercise. American journal of physiology. Regulatory, integrative and comparative physiology. 2014. PMID 25121612. DOI: 10.1152/ajpregu.00180.2014. Access: abstract_metadata. Study: PMID25121612.

38. Angelopoulos P, Diakoronas A, Panagiotopoulos D et al. Cold-Water Immersion and Sports Massage Can Improve Pain Sensation but Not Functionality in Athletes with Delayed Onset Muscle Soreness. Healthcare (Basel, Switzerland). 2022. PMID 36553973. DOI: 10.3390/healthcare10122449. Access: abstract_metadata. Study: PMID36553973.

39. Horgan BG, Tee N, West NP et al. Acute Performance, Daily Well-Being, and Hormone Responses to Water Immersion After Resistance Exercise in Junior International and Subelite Male Volleyball Athletes. Journal of strength and conditioning research. 2023. PMID 37043600. DOI: 10.1519/JSC.0000000000004428. Access: abstract_metadata. Study: PMID37043600.

40. Buijze GA, Sierevelt IN, van der Heijden BC et al. The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial. PloS one. 2016. PMID 27631616. DOI: 10.1371/journal.pone.0161749. Access: full_text_partial. Study: PMID27631616.

41. Zhang S, Zhao Y, Qin Z et al. Transcutaneous Auricular Vagus Nerve Stimulation for Chronic Insomnia Disorder: A Randomized Clinical Trial. JAMA network open. 2024. PMID 39680406. DOI: 10.1001/jamanetworkopen.2024.51217. Access: abstract_metadata. Study: PMID39680406.

42. Stavrakis S, Chakraborty P, Farhat K et al. Noninvasive Vagus Nerve Stimulation in Postural Tachycardia Syndrome: A Randomized Clinical Trial. JACC. Clinical electrophysiology. 2024. PMID 37999672. DOI: 10.1016/j.jacep.2023.10.015. Access: abstract_metadata. Study: PMID37999672.

43. Wang L, Zhang J, Guo C et al. The efficacy and safety of transcutaneous auricular vagus nerve stimulation in patients with mild cognitive impairment: A double blinded randomized clinical trial. Brain stimulation. 2022. PMID 36150665. DOI: 10.1016/j.brs.2022.09.003. Access: abstract_metadata. Study: PMID36150665.

44. Liu C, Tang H, Liu C et al. Transcutaneous auricular vagus nerve stimulation for post-stroke depression: A double-blind, randomized, placebo-controlled trial. Journal of affective disorders. 2024. PMID 38452937. DOI: 10.1016/j.jad.2024.03.005. Access: abstract_metadata. Study: PMID38452937.

45. Liu J, Lv C, Yin M et al. Efficacy and Safety of Transcutaneous Auricular Vagus Nerve Stimulation in Patients With Constipation-Predominant Irritable Bowel Syndrome: A Single-Center, Single-Blind, Randomized Controlled Trial. The American journal of gastroenterology. 2024. PMID 39689011. DOI: 10.14309/ajg.0000000000003257. Access: abstract_metadata. Study: PMID39689011.

46. Yeom JW, Kim H, Park S et al. Transcutaneous auricular vagus nerve stimulation (taVNS) improves sleep quality in chronic insomnia disorder: A double-blind, randomized, sham-controlled trial. Sleep medicine. 2025. PMID 40398066. DOI: 10.1016/j.sleep.2025.106579. Access: abstract_metadata. Study: PMID40398066.

47. Stavrakis S, Stoner JA, Humphrey MB et al. TREAT AF (Transcutaneous Electrical Vagus Nerve Stimulation to Suppress Atrial Fibrillation): A Randomized Clinical Trial. JACC. Clinical electrophysiology. 2020. PMID 32192678. DOI: 10.1016/j.jacep.2019.11.008. Access: full_text_partial. Study: PMID32192678.

48. Shi X, Zhao L, Luo H et al. Transcutaneous Auricular Vagal Nerve Stimulation Is Effective for the Treatment of Functional Dyspepsia: A Multicenter, Randomized Controlled Study. The American journal of gastroenterology. 2024. PMID 37787432. DOI: 10.14309/ajg.0000000000002548. Access: abstract_metadata. Study: PMID37787432.

49. Aranow C, Atish-Fregoso Y, Lesser M et al. Transcutaneous auricular vagus nerve stimulation reduces pain and fatigue in patients with systemic lupus erythematosus: a randomised, double-blind, sham-controlled pilot trial. Annals of the rheumatic diseases. 2021. PMID 33144299. DOI: 10.1136/annrheumdis-2020-217872. Access: abstract_metadata. Study: PMID33144299.

50. Elsehrawy GG, Ibrahim ME, A Moneim NH et al. Transcutaneous vagus nerve stimulation as a pain modulator in knee osteoarthritis: a randomized controlled clinical trial. BMC musculoskeletal disorders. 2025. PMID 39828740. DOI: 10.1186/s12891-025-08288-6. Access: abstract_metadata. Study: PMID39828740.

51. Zuo X, Xu Y, Li S et al. Efficacy and safety of transcutaneous auricular vagus nerve stimulation plus pregabalin for radiotherapy-related neuropathic pain in patients with head and neck cancer (RELAX): a phase 2 randomised trial. EClinicalMedicine. 2025. PMID 40697962. DOI: 10.1016/j.eclinm.2025.103345. Access: abstract_metadata. Study: PMID40697962.

52. Ackland GL, Crane D, Ahuja S et al. Transauricular Vagus Nerve Stimulation in Acute Ischaemic Stroke Requiring Mechanical Thrombectomy: Sham-Controlled, Randomised Device Trial. Translational stroke research. 2025. PMID 41455014. DOI: 10.1007/s12975-025-01404-7. Access: abstract_metadata. Study: PMID41455014.

53. Okdahl T, Kufaishi H, Kornum D et al. Transcutaneous vagus nerve stimulation has no anti-inflammatory effect in diabetes. Scientific reports. 2024. PMID 39251831. DOI: 10.1038/s41598-024-72139-y. Access: abstract_metadata. Study: NCT04143269.

54. Kornum DS, Bertoli D, Kufaishi H et al. Transcutaneous vagal nerve stimulation for treating gastrointestinal symptoms in individuals with diabetes: a randomised, double-blind, sham-controlled, multicentre trial. Diabetologia. 2024. PMID 38546822. DOI: 10.1007/s00125-024-06129-0. Access: abstract_metadata. Study: NCT04143269.

55. Molefi E, McLoughlin I, Palaniappan R. Transcutaneous Auricular Vagus Nerve Stimulation towards Visually Induced Motion Sickness Reduction: A Pilot Study. Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference. 2023. PMID 38083234. DOI: 10.1109/EMBC40787.2023.10340374. Access: abstract_metadata. Study: PMID38083234.

56. Qi M, Huang Y, Mai R et al. Baseline functional connectivity of the basal forebrain-cortical circuit predict taVNS treatment response in primary insomnia: a randomized controlled trial and fMRI study. BMC medicine. 2025. PMID 40629377. DOI: 10.1186/s12916-025-04126-7. Access: abstract_metadata. Study: PMID40629377.

57. Kihara T, Miyata M, Fukudome T et al. Waon therapy improves the prognosis of patients with chronic heart failure. Journal of cardiology. 2009. PMID 19304125. DOI: 10.1016/j.jjcc.2008.11.005. Access: abstract_metadata. Study: PMID19304125.

58. Kunutsor SK, Khan H, Zaccardi F et al. Sauna bathing reduces the risk of stroke in Finnish men and women: A prospective cohort study. Neurology. 2018. PMID 29720543. DOI: 10.1212/WNL.0000000000005606. Access: abstract_metadata. Study: KIHD-later-older-men-and-women.

59. Ukai T, Iso H, Yamagishi K et al. Habitual tub bathing and risks of incident coronary heart disease and stroke. Heart (British Cardiac Society). 2020. PMID 32209614. DOI: 10.1136/heartjnl-2019-315752. Access: abstract_metadata. Study: PMID32209614.

Source-specific evidence cards

[1] Association between sauna bathing and fatal cardiovascular and all-cause mortality events.

Shows: Baseline Finnish sauna frequency and duration in 2315 men were inversely associated with subsequent sudden death, fatal coronary disease and cardiovascular/all-cause mortality over decades.

Does not show: Self-selected exposure, mostly weekly sauna users, one baseline assessment and residual health/social confounding prevent randomized prevention inference; later KIHD reports overlap.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

[2] The Interplay between Systolic Blood Pressure, Sauna Bathing, and Cardiovascular Mortality in Middle-Aged and Older Finnish Men: A Cohort Study.

Shows: KIHD blood-pressure/sauna interaction analysis associated frequent sauna with lower cardiovascular mortality, with limits depending on systolic-pressure threshold.

Does not show: Same cohort family and covariate adjustment do not isolate exposure or show reliable offsetting of established hypertension risk.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

[3] Sauna bathing is associated with reduced cardiovascular mortality and improves risk prediction in men and women: a prospective cohort study.

Shows: A 1688-person older Finnish cohort including women associated sauna frequency/duration with lower cardiovascular mortality after physical-activity and socioeconomic adjustment.

Does not show: Adjustment and improved risk prediction do not eliminate healthy-user bias; setting, baseline-only exposure and overlapping KIHD recruitment constrain independent causal inference.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

[4] Joint associations of sauna bathing and cardiorespiratory fitness on cardiovascular and all-cause mortality risk: a long-term prospective cohort study.

Shows: A 2277-man cohort measured cardiorespiratory fitness and associated frequent sauna plus higher fitness with lower cardiovascular and all-cause mortality.

Does not show: Measuring and adjusting fitness narrows one confounder but does not randomize sauna, eliminate social/health differences or add an independent cohort to overlapping KIHD reports.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

[5] Cardiovascular reactions for whole-body thermal therapy with a hot pack and Waon therapy.

Shows: A nineteen-man randomized crossover compared hot packs and Waon exposure, showing selected temperature, heart-rate and arterial-dilation responses.

Does not show: Acute skin/artery vasodilation and partial modality similarity do not establish clinical-event prevention or general sauna/heat interchangeability.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1.

[6] Effect of Waon therapy on oxidative stress in chronic heart failure.

Shows: Four-week controlled Waon treatment in forty heart-failure patients lowered oxidative markers and BNP with related hamster stress-protein changes.

Does not show: Within-group biomarkers and a disease-model mechanism do not prove reduced mortality/hospitalization; treatment and indication differ from broad sauna prevention.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[7] Effects of repeated sauna treatment on ventricular arrhythmias in patients with chronic heart failure.

Shows: A randomized thirty-person heart-failure trial reduced Holter premature-ventricular-contraction counts and improved selected HRV/BNP measures after repeated supervised infrared sauna.

Does not show: Ectopy burden is a rhythm endpoint, not demonstrated fewer sudden deaths or major clinical events; small unequal arms and short follow-up limit broad prevention claims.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[8] Safety, acceptance, and physiologic effects of sauna bathing in people with chronic heart failure: a pilot report.

Shows: A nine-person supervised sauna crossover reported tolerability but no significant between-group exercise-endurance or heart-failure-questionnaire benefit; only one neuroendocrine contrast was significant.

Does not show: Pilot size yields imprecise nulls and does not establish equivalence or safety for all heart-failure patients or temperatures.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[9] Waon Therapy for Managing Chronic Heart Failure　- Results From a Multicenter Prospective Randomized WAON-CHF Study.

Shows: The 149-person multicenter WAON-CHF randomized trial found selected secondary NYHA/walking/cardiothoracic improvements, but the primary between-group BNP change was not significant.

Does not show: Primary-negative short inpatient adjunct therapy cannot be presented as an event-prevention success or transferred to unsupervised Finnish sauna.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[10] Beneficial effects of Waon therapy on patients with chronic heart failure: results of a prospective multicenter study.

Shows: A 188-person multicenter Waon report found cardiac/BNP and symptom changes during adjunct treatment; several clinical measures improved in both groups.

Does not show: Many results are within-group contrasts; improvement in one group and not another is not proof of a significant treatment difference, and hard events were not established.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[11] Thermal hydrotherapy improves quality of life and hemodynamic function in patients with chronic heart failure.

Shows: Fifteen mild-heart-failure patients in a randomized crossover warm/cold hydrotherapy bundle had selected quality-of-life, symptom and exercise heart-rate improvements.

Does not show: A mixed thermal home program does not isolate cold immersion or sauna, and subjective bundle effects do not prove cardiovascular-event prevention.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC4.

[12] Exposure to passive heat and cold stress differentially modulates cerebrovascular-CO2 responsiveness.

Shows: Randomized thermal-condition experiments in sixteen adults found different heat/cold effects on cerebral CO2 responsiveness and perfusion-pressure regulation.

Does not show: Acute cerebrovascular physiology includes adverse-perfusion potential and cannot establish durable cardiovascular or health benefit.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC4.

[13] Cerebrovascular and corticomotor function during progressive passive hyperthermia in humans.

Shows: Progressive passive hyperthermia in eight adults reduced cerebral perfusion, voluntary contraction and cortical activation; CO2 restoration partly restored motor measures.

Does not show: Extreme acute heat with mechanistic rescue demonstrates functional strain, not evidence that usual sauna causes harm or prevents events.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1.

[14] Passive muscle heating attenuates the decline in vascular function caused by limb disuse.

Shows: A twenty-one-person sham-controlled disuse trial found local diathermy heating attenuated femoral vascular-function decline during immobilization.

Does not show: Localized muscle heating and vascular measures do not establish sauna prevention, added capillary density or reduced clinical events.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1.

[15] Plasma compartment filling after exercise or heat exposure.

Shows: Randomized heat/exercise dehydration and rehydration experiments in eight subjects found different plasma-volume restoration profiles.

Does not show: Acute fluid-compartment responses inform thermal strain, not durable event prevention or a sauna dosing recommendation.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1.

[16] Heat therapy vs. supervised exercise therapy for peripheral arterial disease: a 12-wk randomized, controlled trial.

Shows: A twenty-two-person PAD randomized comparison of heat-plus-calisthenics and supervised exercise found walking/BP improvements in both arms without significant between-arm functional differences.

Does not show: No nonexercise control and different cointervention doses prevent attributing benefit solely to heat; hot-water therapy is not sauna and no event reduction was tested.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[17] Acute effects of passive heat exposure on vascular function and exercise capacity in patients with chronic kidney disease.

Shows: A ten-person CKD randomized crossover found greater vascular responses and six-minute walking distance after a single infrared-sauna exposure than thermoneutral control.

Does not show: Acute pilot function and reassuring short kidney markers do not establish sustained benefit or reduced cardiovascular events.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[18] Acute effect of passive heat exposure on markers of cardiometabolic function in adults with type 2 diabetes mellitus.

Shows: Hot-water versus thermoneutral crossover in thirteen adults with diabetes increased thermal strain but did not improve insulin sensitivity, FMD or selected cardiometabolic markers acutely.

Does not show: The single exposure and another heat modality constrain chronic sauna inference; null markers do not prove all heat benefits absent.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[19] Acute vascular function responses predict chronic vascular function changes to heating and exercise interventions in young, healthy recreationally active adults.

Shows: A secondary analysis of forty-five randomized heating/exercise participants associated acute vascular responses with chronic changes in the same indices.

Does not show: Correlated responses do not prove mediation or structural remodeling; same-parent trial and proxy prediction are not clinical-event prevention.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1.

[20] Six weeks of localized passive heat therapy elicits some exercise-like improvements in resistance artery function.

Shows: Six-week randomized local heating/sham/exercise comparison improved selected resistance-artery measures with heating but not exercise power; exercise improved power and angiogenesis.

Does not show: Vascular proxy benefits are not functional-training equivalence or hard-event prevention, and local heating differs from sauna.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[21] Passive heat therapy in sedentary humans increases skeletal muscle capillarization and eNOS content but not mitochondrial density or GLUT4 content.

Shows: Six-week passive heat and exercise in twenty sedentary young men improved capillarization/eNOS and selected aerobic/insulin measures; heat did not reproduce mitochondrial/GLUT4 changes.

Does not show: Small active-comparator study with no untreated arm does not establish sauna clinical prevention or complete exercise mimicry.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[22] Post-exercise hot water immersion enhances haemodynamic and vascular benefits of exercise without further improving cardiorespiratory fitness, glucose, lipids or inflammation.

Shows: A twenty-four-person randomized exercise-plus-hot-water versus exercise-plus-thermoneutral trial improved BP/FMD more with heat, without extra fitness, glucose, lipid or inflammation benefit.

Does not show: The added thermal water intervention has specific intermediate endpoints; it does not show sauna-alone mortality benefit.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[23] Lower-limb hot-water immersion acutely induces beneficial hemodynamic and cardiovascular responses in peripheral arterial disease and healthy, elderly controls.

Shows: Acute hot-water exposure in PAD patients and older controls increased limb perfusion/shear and transiently lowered blood pressure.

Does not show: Acute within-condition physiological responses are not a controlled clinical-event outcome or proof of lasting safer vascular disease trajectory.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1.

[24] Comparison between exercise and hot water immersion on skin microvascular responses in older adults with overweight and obesity.

Shows: A randomized older-adult crossover found greater acute skin-microvascular changes with hot-water immersion than time-matched exercise.

Does not show: Skin perfusion and thermal strain measured by OCT are not long-term cardiovascular function or event prevention.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1.

[25] Effects of regular sauna bathing in conjunction with exercise on cardiovascular function: a multi-arm, randomized controlled trial.

Shows: The forty-seven-analyzed-participant randomized exercise-plus-sauna arm had lower systolic BP/cholesterol and higher estimated cardiorespiratory fitness than exercise alone after eight weeks.

Does not show: Fitness was estimated from a submaximal heart-rate test rather than directly measured maximal oxygen uptake; predominantly female sample, bundle exposure and no events limit prevention transfer.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. Selected body sections: 1:MATERIALS AND METHODS:paragraph0, 1:MATERIALS AND METHODS:paragraph2, 1:MATERIALS AND METHODS:paragraph5, 1:MATERIALS AND METHODS:paragraph11, 1:MATERIALS AND METHODS:paragraph14, 2:RESULTS:paragraph3, 2:RESULTS:paragraph6. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[26] Effects of Sauna bathing on Exercise Capacity and Muscle Function in HFpEF.

Shows: An eighteen-completer uncontrolled HFpEF sauna pilot showed exercise/walking/strength and selected quality-of-life improvements, with partial loss after withdrawal.

Does not show: Withdrawal after an open before-after course does not isolate treatment from practice, regression or co-care; a large controlled trial was described as planned, not underway.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[27] Hemodynamics of post-exercise vs. post hot water immersion recovery.

Shows: A randomized-order twelve-person comparison found overlapping and distinct postexercise versus hot-water recovery hemodynamics.

Does not show: Similar acute recovery variables do not establish shared long-term causal health effects or exercise replacement.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1.

[28] Finnish sauna bathing and vascular health of adults with coronary artery disease: a randomized controlled trial.

Shows: An eight-week forty-one-person randomized Finnish-sauna CAD trial achieved heat acclimation without improved FMD, arterial stiffness or blood pressure; reactive-hyperemia contrasts did not support benefit.

Does not show: A genuine disease-context null constrains mechanism generalization, but it does not directly test mortality or prove no possible prevention benefit.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[29] Infrared sauna as exercise-mimetic? Physiological responses to infrared sauna vs exercise in healthy women: A randomized controlled crossover trial.

Shows: A ten-woman controlled crossover found greater thermal response with infrared sauna but no significant BP, arterial-stiffness or HRV difference versus resting or exercise conditions.

Does not show: Infrared thermal strain is not complete exercise mimicry; small acute nulls are imprecise and do not adjudicate long-term cardiovascular events.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1.

[30] Effects of sauna alone and postexercise sauna baths on blood pressure and hemodynamic variables in patients with untreated hypertension.

Shows: A sixteen-person hypertension comparison found acute vascular-resistance reductions with sauna and selected ambulatory-BP effects with exercise plus sauna.

Does not show: Combined exposure and brief hemodynamic follow-up do not isolate sauna-alone chronic disease or clinical-event prevention.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[31] Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training.

Shows: A twelve-week randomized strength-training comparison found smaller strength/mass gains with repeated cold-water recovery than active recovery, with separate acute mechanistic findings.

Does not show: Male training-specific harm does not prove all cold use harmful; it directly challenges equating acute recovery or hormetic stress with durable training benefit.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC4.

[32] Cold- and hot-water immersion are not more effective than placebo for the recovery of physical performance and training adaptations in national level soccer players.

Shows: Randomized soccer-player cold/hot-water versus sham-laser recovery showed no superiority in acute performance recovery or fifteen-week adaptation.

Does not show: Young male athletes and small longer-term completer sample do not establish equivalence or all-population health outcomes.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC4.

[33] Effect of repeated post-resistance exercise cold or hot water immersion on in-season inflammatory responses in academy rugby players: a randomised controlled cross-over design.

Shows: A rugby-player randomized crossover found selected creatine-kinase, inflammatory and growth-factor differences after cold/hot-water recovery.

Does not show: Biochemical changes and small effects do not establish performance, clinical or durable-health benefit; hydrostatic and period effects remain.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC4.

[34] Strength training adaptations after cold-water immersion.

Shows: Seventeen men with randomized leg cooling during strength training showed small trends toward poorer cooled-leg strength gains and retention.

Does not show: Key leg/interaction tests were not conventionally significant; findings should not be described as a definitive strength-harm replication or a broad health effect.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC4.

[35] Does Cold-Water Immersion After Strength Training Attenuate Training Adaptation?

Shows: An eleven-person randomized training crossover found poorer muscle-thickness adaptation with cooling and nonsignificant strength/jump contrasts with wide intervals.

Does not show: Small sample and carryover/washout assumptions limit precise durable effect sizes; it is not a cardiovascular or sauna-comparability test.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC4.

[36] Does Regular Post-exercise Cold Application Attenuate Trained Muscle Adaptation?

Shows: A fourteen-man forearm training comparison found attenuated thickness and selected strength/vascular adaptation with postexercise cooling.

Does not show: Local muscle exposure and small allocation groups do not support a universal cold-health harm or sauna-equivalence claim.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC4.

[37] Cold water immersion enhances recovery of submaximal muscle function after resistance exercise.

Shows: A ten-man randomized crossover found better selected submaximal work six hours after cold immersion, without enhanced maximal-function recovery.

Does not show: An acute performance benefit is retained but does not establish improved long-term training adaptation or durable health comparable to sauna.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC4.

[38] Cold-Water Immersion and Sports Massage Can Improve Pain Sensation but Not Functionality in Athletes with Delayed Onset Muscle Soreness.

Shows: A sixty-man randomized soreness study found lower pain with cold recovery but no benefit in most functional or muscle-damage measures.

Does not show: Unblinded symptom relief is distinct from functional recovery and cannot establish durable clinical benefit.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC4.

[39] Acute Performance, Daily Well-Being, and Hormone Responses to Water Immersion After Resistance Exercise in Junior International and Subelite Male Volleyball Athletes.

Shows: A volleyball-athlete randomized crossover showed selected perceptions and small performance-treatment effects across immersion conditions, with no significant intervention-by-time interactions.

Does not show: Within-condition and main effects should not be inflated into clear between-treatment adaptation benefits; short follow-up and variability constrain transfer.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC4.

[40] The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial.

Shows: The 3018-person unblinded cold-shower trial reduced self-reported sickness absence by 29 percent but not overall illness days; original Methods confirm self-report and retrospective registration before analysis.

Does not show: Work attendance is not fewer infections or cardiovascular benefit; no sauna comparison, blinding or verified adherence establishes durable comparable health effects, and the linked correction adds omitted underlying Table 2 data without an asserted endpoint revision.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. Selected body sections: 1:Methods:paragraph0, 1:Methods:paragraph1, 1:Methods:paragraph3, 1:Methods:paragraph4, 1:Methods:paragraph10, 2:Results:paragraph0, 2:Results:paragraph1, 2:Results:paragraph2, 2:Results:paragraph4, 2:Results:paragraph20. No complete-paper or supplement audit claimed. ErratumIn: PMID30071104. Subclaims: SC4.

[41] Transcutaneous Auricular Vagus Nerve Stimulation for Chronic Insomnia Disorder: A Randomized Clinical Trial.

Shows: A seventy-two-person sham-controlled auricular-stimulation insomnia trial improved PSQI beyond sham over eight weeks with sustained symptom findings.

Does not show: A defined clinical symptom trial does not establish every consumer device or implanted-VNS equivalence; sensation matching, allocation guessing and objective sleep/function require separate checks.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[42] Noninvasive Vagus Nerve Stimulation in Postural Tachycardia Syndrome: A Randomized Clinical Trial.

Shows: A twenty-six-woman sham-controlled POTS trial reduced measured postural tachycardia with defined tragus stimulation over two months.

Does not show: A specific disease/device exposure and physiological endpoint do not establish broad consumer wellness claims or eliminate mediation alternatives.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[43] The efficacy and safety of transcutaneous auricular vagus nerve stimulation in patients with mild cognitive impairment: A double blinded randomized clinical trial.

Shows: A small controlled MCI trial favored auricular stimulation on selected cognitive scores after twenty-four weeks.

Does not show: Cognitive-score changes and many within-arm secondary contrasts do not prove prevention of dementia or clinical equivalence across devices.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[44] Transcutaneous auricular vagus nerve stimulation for post-stroke depression: A double-blind, randomized, placebo-controlled trial.

Shows: An eighty-patient poststroke-depression report favored adjunct taVNS on symptom/function measures and biomarkers.

Does not show: Abstract describes double-blind sham design but also conventional-treatment-only controls; comparator credibility requires body verification before a firm causal threshold, and biomarkers do not isolate mediation.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[45] Efficacy and Safety of Transcutaneous Auricular Vagus Nerve Stimulation in Patients With Constipation-Predominant Irritable Bowel Syndrome: A Single-Center, Single-Blind, Randomized Controlled Trial.

Shows: A forty-person single-blind IBS-C trial favored defined taVNS on bowel/symptom and rectal measures alongside multiomics changes.

Does not show: Small single-center multiple endpoints and observed mediator correlations do not establish a universal vagal mechanism or consumer-device equivalence.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[46] Transcutaneous auricular vagus nerve stimulation (taVNS) improves sleep quality in chronic insomnia disorder: A double-blind, randomized, sham-controlled trial.

Shows: A forty-person sham-controlled insomnia study favored taVNS on symptom scores and selected wearable-derived sleep/QoL outcomes.

Does not show: Small modified-intention-to-treat study and consumer wearable measures do not validate all brands or objectively confirm sleep physiology; abstract numerical signs/units need body checking before carrying precise estimates.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[47] TREAT AF (Transcutaneous Electrical Vagus Nerve Stimulation to Suppress Atrial Fibrillation): A Randomized Clinical Trial.

Shows: The 53-person TREAT-AF trial used a named home Parasym device with tragus versus earlobe stimulation and blinded outcome assessors; ECG-patch AF burden was lower at six months.

Does not show: This is a genuine specific-device/indication positive, not proof every consumer stimulation reproduces implanted benefits or prevents stroke/death; intermittent ECG windows and small sample remain.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. Selected body sections: 0:Methods:paragraph0, 0:Methods:paragraph1, 0:Methods:paragraph2, 0:Methods:paragraph3, 0:Methods:paragraph6, 0:Methods:paragraph7, 1:Results:paragraph0, 1:Results:paragraph1, 1:Results:paragraph2, 1:Results:paragraph3, 1:Results:paragraph6. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[48] Transcutaneous Auricular Vagal Nerve Stimulation Is Effective for the Treatment of Functional Dyspepsia: A Multicenter, Randomized Controlled Study.

Shows: A three-hundred-person randomized functional-dyspepsia trial favored defined 10/25 Hz taVNS on prespecified symptom response and adequate relief versus sham.

Does not show: Specific dose/site and diagnosed symptoms cannot be transferred to all products, diseases or cardiovascular-event prevention; blinding integrity remains separate from randomized labeling.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[49] Transcutaneous auricular vagus nerve stimulation reduces pain and fatigue in patients with systemic lupus erythematosus: a randomised, double-blind, sham-controlled pilot trial.

Shows: An eighteen-person sham-controlled lupus pilot improved selected pain/fatigue/joint scores but most inflammatory mediators did not change.

Does not show: Small short symptom benefit does not establish a general anti-inflammatory mechanism or device-class equivalence; a linked correction remains attached.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. ErratumIn: PMID34412029. Subclaims: SC5.

[50] Transcutaneous vagus nerve stimulation as a pain modulator in knee osteoarthritis: a randomized controlled clinical trial.

Shows: A sixty-eight-person knee-osteoarthritis taVNS/sham trial reported selected pain/functional improvements, largely as within-group contrasts.

Does not show: Significance within active but not sham arms is not a demonstrated between-arm treatment difference; device and indication transfer remain unestablished.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[51] Efficacy and safety of transcutaneous auricular vagus nerve stimulation plus pregabalin for radiotherapy-related neuropathic pain in patients with head and neck cancer (RELAX): a phase 2 randomised trial.

Shows: The 116-person multicenter RELAX trial found greater seven-day pain reduction with taVNS plus pregabalin than sham plus pregabalin.

Does not show: Adjunct short pain relief in cancer survivors does not establish standalone long-term consumer efficacy or isolate the proposed vagal mediator.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[52] Transauricular Vagus Nerve Stimulation in Acute Ischaemic Stroke Requiring Mechanical Thrombectomy: Sham-Controlled, Randomised Device Trial.

Shows: A thirty-six-person blinded stroke-thrombectomy trial did not change its primary 24-hour systolic-pressure-variability outcome despite molecular/HRV changes.

Does not show: Safety/feasibility and gene effects are not success on the primary endpoint or proof of a durable neurological/device benefit.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[53] Transcutaneous vagus nerve stimulation has no anti-inflammatory effect in diabetes.

Shows: A secondary randomized-diabetes analysis found no active-versus-sham inflammatory-cytokine effect over short and longer stimulation periods.

Does not show: Same-parent NCT04143269 evidence is not a new independent clinical trial; a near-significant subgroup trend does not reverse the whole-sample null.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[54] Transcutaneous vagal nerve stimulation for treating gastrointestinal symptoms in individuals with diabetes: a randomised, double-blind, sham-controlled, multicentre trial.

Shows: A 145-randomized-person multicenter cervical-stimulation diabetes trial found no greater gastrointestinal symptom reduction than sham over either period.

Does not show: A defined null constrains broad device/mechanism transfer but does not negate successes in different indications; gastric-emptying change did not establish symptom benefit.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[55] Transcutaneous Auricular Vagus Nerve Stimulation towards Visually Induced Motion Sickness Reduction: A Pilot Study.

Shows: A fifteen-person sham-controlled motion-sickness pilot found selected EEG and symptom-score effects.

Does not show: Small acute symptom and EEG findings do not establish chemotherapy efficacy, broad durable health benefit or equivalence to established medical stimulation.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[56] Baseline functional connectivity of the basal forebrain-cortical circuit predict taVNS treatment response in primary insomnia: a randomized controlled trial and fMRI study.

Shows: A randomized insomnia study favored real taVNS on symptom scales and related fMRI connectivity, with exploratory independently tested prediction.

Does not show: Connectivity correlation/prediction is not mediator manipulation or necessity; it does not establish all-device equivalence or durable functional recovery.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5.

[57] Waon therapy improves the prognosis of patients with chronic heart failure.

Shows: In 129 NYHA III/IV heart-failure patients, 64 supervised Waon recipients and 65 age/gender/NYHA-matched traditional-care controls had five-year HF or cardiac-death composite rates 31.3% versus 68.7%; deaths were eight versus twelve.

Does not show: No random allocation stated; matched advanced-HF adjunct treatment with continued postdischarge exposure is not habitual sauna primary prevention. Selection, co-care and composite components remain unresolved; deaths alone do not establish isolated mortality reduction.

Access/status: Bounded original primary abstract Results/Findings/conclusion passages and linked-status metadata examined; no complete-abstract audit asserted. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

[58] Sauna bathing reduces the risk of stroke in Finnish men and women: A prospective cohort study.

Shows: Baseline sauna frequency in 1628 KIHD men and women without prior stroke was inversely associated with 155 incident strokes over a median 14.9 years; HR 0.38 (0.18-0.81) for 4-7 versus 1 session per week after risk-factor, physical-activity and socioeconomic adjustment.

Does not show: Self-selected baseline exposure in the same KIHD cohort family as refs 1-4; adds an incident (non-mortality) endpoint, not an independent cohort or causal allocation. PubMed indexes the article type as Editorial although the abstract reports a prospective cohort.

Access/status: Bounded original primary abstract and PubMed metadata examined via PubMed get_article_metadata on 2026-11-02 (added under adversarial finding S5); no complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

[59] Habitual tub bathing and risks of incident coronary heart disease and stroke.

Shows: In 30,076 Japanese adults aged 40-59 without CVD or cancer, almost-daily tub bathing versus 0-2 times per week was associated with lower incident CVD (HR 0.72, 0.62-0.84), CHD and total stroke over 538,373 person-years; no association with sudden cardiac death.

Does not show: Hot-water tub bathing, not sauna; observational with self-reported baseline bathing frequency and residual confounding. Bears on geographic replication of the heat-exposure association, not on sauna causation.

Access/status: Bounded original primary abstract and PubMed metadata examined via PubMed get_article_metadata on 2026-11-02 (added under adversarial finding S5); no complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

Documentary record

Every grade on this site is reproducible from its record. The files below are the posted edition exactly as assessed.

• ADVERSARIAL_REVIEW.sauna-cardiovascular-prevention.md
• CONSENSUS_CROSSCHECK.html
• CONSENSUS_CROSSCHECK.md
• RESEARCH_TIMELINE.html
• RESEARCH_TIMELINE.md
• SHA256.txt
• adversarial-findings.sauna-cardiovascular-prevention.json
• codex-correction-provenance.json
• consensus-validation.json
• edition-approval-audit.json
• reader-summary.json
• research-timeline.json
• sauna-cardiovascular-prevention.review.md
• sauna-cardiovascular-prevention.scorecard.json
• validation-report.json
• validation-round2-2026-10-14.json
• validation.txt
• video-insert.md
• web-page.md

Sources: 59 · load-bearing claims: 65 · verified: 65 · unverified: 0 · contradicted: 0 · schema 5.3