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Sauna Hype°H

The claim

“The first minute in cold water is the most dangerous part.”

Solid. Dropping suddenly into cold water makes you gasp and then breathe fast and hard in a way you can't control. That response peaks in the first minute, and breathing control usually comes back after about a minute. Water-safety researchers blame this cold shock for about 60% of deaths in the first minutes of immersion.

Updated Sep 24, 2026 · 1 study reviewed

Good human studies back it, and the claim says what they found.

People say it in places like these

  • Water-safety campaigns

    If you fall in, float for the first minute and let the gasping pass.

  • The Guardian

    Mike Tipton says about 60% of deaths in cold water happen in the first minute of immersion.

    See an example ↗

The research found this

Cold water on the skin triggers a gasp and then fast, heavy breathing that you can't control. In a controlled lab study, men new to cold water were breathing 47 times a minute in their first 30 seconds at 10°C. Their hearts were beating 128 times a minute.Source 1 · Clinical trialPermanence of the habituation of the initial responses to cold-water immersion in humansTipton MJ, Mekjavic IB, Eglin CM. European Journal of Applied Physiology, 2000.Read the paper ↗PubMed ↗ One gasp can pull in 2 to 3 liters of air, and a breath hold that lasts 45 to 60 seconds on land can shrink to less than one second in cold water.Source 2 · ReviewExtreme environmental physiology in the dockTipton M. Medico-Legal Journal, 2024.Read the paper ↗PubMed ↗

Cold shock can kill long before hypothermia sets in, and a 1989 review judged it probably responsible for most open-water immersion deaths.Source 3 · ReviewThe Initial Responses to Cold-Water Immersion in ManTipton MJ. Clinical Science, 1989.Read the paper ↗PubMed ↗ The lifeboat charity RNLI built its Float to Live campaign on lab work by researchers who attribute around 60% of deaths in the first minutes of immersion to cold shock. They also note that hypothermia takes at least 30 minutes to develop, even in the coldest water.Source 4 · Review‘From lab to lifesaving’: the evolution of a public health campaign to reduce drowningsTipton M, Barwood M, Eglin C, et al.. Injury Prevention, 2026.Read the paper ↗PubMed ↗ A 1977 UK Home Office review they cite found that about 55% of open-water deaths happened within 3 meters of safety, and that two-thirds of the victims had been considered good swimmers.

Holding your breath with your face in cold water adds a second danger. Cold on the face sets off the diving reflex, which slows the heart, and cold on the body drives the heart faster. Together they produced abnormal heart rhythms in 62–82% of submersions in young, fit volunteers.Source 5 · Review‘Autonomic conflict’: a different way to die during cold water immersion?Shattock MJ, Tipton MJ. The Journal of Physiology, 2012.Read the paper ↗PubMed ↗ Head-out immersion with normal breathing produced them in about 2%. When Swedish teenagers held their breath with their faces in 10°C water, their heart rates dropped by 68 beats a minute on average.Source 6 · Cross-sectional studyAssessment of arrhythmias and heart rate response in healthy adolescents performing face immersion and body submersion in ice‐cold waterLundström A, Karlsson M, Rydberg A, et al.. Physiological Reports, 2025.Read the paper ↗PubMed ↗

The response fades with practice. In one study, six extra three-minute immersions over four days roughly halved the breathing response, and the drop was still there seven months later.Source 1 · Clinical trialPermanence of the habituation of the initial responses to cold-water immersion in humansTipton MJ, Mekjavic IB, Eglin CM. European Journal of Applied Physiology, 2000.Read the paper ↗PubMed ↗ A 2024 pooled analysis found that people adapted after about four immersions, and their heart rate responses fell by 14 beats a minute.Source 7 · Meta-analysisHabituation of the cold shock response: A systematic review and meta-analysisBarwood MJ, Eglin C, Hills SP, et al.. Journal of Thermal Biology, 2024.Read the paper ↗PubMed ↗ When volunteers took six cold showers instead, water at 10°C cut the breathing rate response to a later plunge by 21% and water at 15°C left it unchanged.Source 8 · Randomized trialRepeated cold showers as a method of habituating humans to the initial responses to cold water immersionEglin CM, Tipton MJ. European Journal of Applied Physiology, 2005.Read the paper ↗PubMed ↗

In a setting closer to a plunge, Swiss researchers monitored 20 middle-aged swimmers across 64 sessions in 7°C water. Their heart rates rose 40 beats a minute, and no sustained or serious rhythm problems appeared.Source 9 · Clinical trialCardiac arrhythmia during cold-water immersion: a self-controlled field study with extended rhythm monitoringMerkt B, Craviari C, Baggish AL, et al.. Journal of Exercise Science & Fitness, 2026.Read the paper ↗PubMed ↗ We found no case report in the medical literature of a death in a home cold-plunge tub. As of September 2026, US Consumer Product Safety Commission recall records showed no plunge tub recalled for electric shock or drowning.

The dial reads 18°H for four reasons

How the reading adds up

6 + 6 + 2 + 4 = 18°H

  1. EvidenceWhat kind of human evidence exists?

    6/25

    Controlled lab studies have measured the cold shock response in volunteers, and a 2024 analysis pooled 17 groups of them.Source 1 · Clinical trialPermanence of the habituation of the initial responses to cold-water immersion in humansTipton MJ, Mekjavic IB, Eglin CM. European Journal of Applied Physiology, 2000.Read the paper ↗PubMed ↗Source 7 · Meta-analysisHabituation of the cold shock response: A systematic review and meta-analysisBarwood MJ, Eglin C, Hills SP, et al.. Journal of Thermal Biology, 2024.Read the paper ↗PubMed ↗ The link to deaths comes from drowning records and expert estimates, and some of those records are decades old.Source 4 · Review‘From lab to lifesaving’: the evolution of a public health campaign to reduce drowningsTipton M, Barwood M, Eglin C, et al.. Injury Prevention, 2026.Read the paper ↗PubMed ↗

  2. ConsistencyHave other studies found the same thing?

    6/25

    Lab studies agree on the size and timing of the response, and most of them come from one UK group.Source 10 · Clinical trialTemperature dependence of habituation of the initial responses to cold-water immersionTipton MJ, Golden FSC, Higenbottam C, et al.. European Journal of Applied Physiology, 1998.Read the paper ↗PubMed ↗Source 1 · Clinical trialPermanence of the habituation of the initial responses to cold-water immersion in humansTipton MJ, Mekjavic IB, Eglin CM. European Journal of Applied Physiology, 2000.Read the paper ↗PubMed ↗Source 8 · Randomized trialRepeated cold showers as a method of habituating humans to the initial responses to cold water immersionEglin CM, Tipton MJ. European Journal of Applied Physiology, 2005.Read the paper ↗PubMed ↗ Outside the lab, a Swiss study recorded heart rate rising 40 beats a minute in 7°C water.Source 9 · Clinical trialCardiac arrhythmia during cold-water immersion: a self-controlled field study with extended rhythm monitoringMerkt B, Craviari C, Baggish AL, et al.. Journal of Exercise Science & Fitness, 2026.Read the paper ↗PubMed ↗

  3. MagnitudeDoes the claim match the size of the effect?

    2/25

    The claim matches how the researchers describe it. They say the response is greatest in the first minute and that hypothermia takes at least 30 minutes to develop, even in the coldest water.Source 4 · Review‘From lab to lifesaving’: the evolution of a public health campaign to reduce drowningsTipton M, Barwood M, Eglin C, et al.. Injury Prevention, 2026.Read the paper ↗PubMed ↗

  4. DoseDoes the studied dose match how people use it?

    4/25

    The lab work used head-out immersion at 10–15°C, and a home plunge runs close to that.Source 10 · Clinical trialTemperature dependence of habituation of the initial responses to cold-water immersionTipton MJ, Golden FSC, Higenbottam C, et al.. European Journal of Applied Physiology, 1998.Read the paper ↗PubMed ↗ The death figures come from open water, where one gasp with your face under can be fatal, and a tub lets you keep your head up and stand.Source 2 · ReviewExtreme environmental physiology in the dockTipton M. Medico-Legal Journal, 2024.Read the paper ↗PubMed ↗

The claim drifts from the data here

The 60% figure is those researchers' own estimate, and the Home Office numbers behind the campaign date from 1977.Source 4 · Review‘From lab to lifesaving’: the evolution of a public health campaign to reduce drowningsTipton M, Barwood M, Eglin C, et al.. Injury Prevention, 2026.Read the paper ↗PubMed ↗ National drowning counts can't check it, because they don't separate out cold water or cold shock. The US records about 4,000 unintentional drowning deaths a year, and the UK logged 5,051 water deaths from 2012 to 2019.Source 11 · DatasetDrowning FactsUS Centers for Disease Control and Prevention. US Centers for Disease Control and Prevention, 2026.Read the paper ↗Source 12 · DatasetThe water incident database (WAID) 2012 to 2019: a systematic evaluation of the documenting of UK drowningsHills SP, Hobbs M, Tipton MJ, et al.. BMC Public Health, 2021.Read the paper ↗PubMed ↗

Being able to stand with your head up makes the gasp less dangerous in a home tub than in open water. The bigger risks in a tub come from breath holds and face dunks, which set the diving reflex against the cold shock, and from hyperventilation drills that can cause a blackout.Source 5 · Review‘Autonomic conflict’: a different way to die during cold water immersion?Shattock MJ, Tipton MJ. The Journal of Physiology, 2012.Read the paper ↗PubMed ↗Source 13 · ReviewThe physiology of survival: Breath‐hold shallow‐water divingBaker AH, Jones A, Mayhew A, et al.. Experimental Physiology, 2026.Read the paper ↗ Cold urticaria, where the skin breaks out in hives from cold, adds a different risk. Of people with the typical form, 37% had cold-induced anaphylaxis (a severe allergic reaction), and full immersion in cold water was the most common trigger.Source 14 · Cross-sectional studyRisk factors for systemic reactions in typical cold urticaria: Results from the COLD‐CE studyBizjak M, Košnik M, Dinevski D, et al.. Allergy, 2022.Read the paper ↗PubMed ↗

Put it to use

Keep your head above water and let the fast breathing settle through the first minute.Source 4 · Review‘From lab to lifesaving’: the evolution of a public health campaign to reduce drowningsTipton M, Barwood M, Eglin C, et al.. Injury Prevention, 2026.Read the paper ↗PubMed ↗ Don't hold your breath or put your face under, and keep hyperventilation drills on dry land. If you have a heart condition or have ever broken out in hives from cold, check with a doctor first.Source 5 · Review‘Autonomic conflict’: a different way to die during cold water immersion?Shattock MJ, Tipton MJ. The Journal of Physiology, 2012.Read the paper ↗PubMed ↗Source 14 · Cross-sectional studyRisk factors for systemic reactions in typical cold urticaria: Results from the COLD‐CE studyBizjak M, Košnik M, Dinevski D, et al.. Allergy, 2022.Read the paper ↗PubMed ↗

From our sister magazine

Sauna Monthly compares the plunge tubs it tracks on price and cooling

Sauna Monthly · Guide

These cold plunge tubs are worth buying

Sauna Monthly picks its favorites and names the spec that decides between them.

Read it on Sauna Monthly

Sauna Monthly · Shop

Cold plunge tubs range from ice barrels to chillers

Sauna Monthly compares every tub it tracks on price and cooling.

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People also ask

How long does cold shock last?

The gasp and fast breathing are at their worst in the first minute, and breathing control usually returns after about a minute. The skin's cold sensors take roughly two minutes to adapt.Source 4 · Review‘From lab to lifesaving’: the evolution of a public health campaign to reduce drowningsTipton M, Barwood M, Eglin C, et al.. Injury Prevention, 2026.Read the paper ↗PubMed ↗

Is it dangerous to put your head under in a cold plunge?

It adds risk. Cold water on the face during a breath hold triggers the diving reflex at the same time as the cold shock. In healthy volunteers that combination produced abnormal heart rhythms in 62–82% of submersions, against about 2% with the head out and normal breathing.Source 5 · Review‘Autonomic conflict’: a different way to die during cold water immersion?Shattock MJ, Tipton MJ. The Journal of Physiology, 2012.Read the paper ↗PubMed ↗

Is a cold plunge safe with a heart condition?

Check with your doctor first, because the evidence is thin. Trials of cold water routinely exclude people with heart disease.Source 15 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗Source 16 · Randomized trialImproved Mood Following Cold‐Water Immersion: A Comparison of Differing Exposure DurationsKelly JS, Davidson N, Delaney JP. Lifestyle Medicine, 2026.Read the paper ↗ In one supervised study, men with chronic heart failure or coronary artery disease tolerated two saunas followed by a 12°C immersion, and their systolic blood pressure (the top number) rose.Source 17 · Clinical trialAcute effects of Finnish sauna and cold-water immersion on haemodynamic variables and autonomic nervous system activity in patients with heart failureRadtke T, Poerschke D, Wilhelm M, et al.. European Journal of Preventive Cardiology, 2016.Read the paper ↗PubMed ↗ Reviews warn that people with known or hidden heart disease risk abnormal heart rhythms in cold water.Source 18 · ReviewWinter Swimming: Body Hardening and Cardiorespiratory Protection Via Sustainable AcclimationManolis AS, Manolis SA, Manolis AA, et al.. Current Sports Medicine Reports, 2019.Read the paper ↗PubMed ↗

Check these claims next

89°H

Hot air

Cold

“Eleven minutes of cold a week is the ideal dose.”

A 2021 paper added up the cold-water habits that seven Danish winter swimmers reported and got 11 minutes a week. The study never assigned or compared a dose, and in the lab it cooled people with blankets that had cold water running through them.

56°H

Unsettled

Cold

“Splashing cold water on your face resets your vagus nerve.”

Cold water on the face sets off the diving reflex, and the vagus nerve slows the heart within seconds. In the studies the vagal effects last up to about 15 minutes, so the research gives no sign of a lasting reset.

56°H

Unsettled

Cold

“The Wim Hof Method lets you control your immune system.”

Men trained in the method had a smaller inflammatory response to an injected bacterial toxin, and the breathing did most of the work. In a later trial, cold training alone left that response unchanged, and no study has tracked whether practitioners get sick less.

We cited these sources

  1. 01Tipton MJ, Mekjavic IB, Eglin CM. Permanence of the habituation of the initial responses to cold-water immersion in humans. European Journal of Applied Physiology. 2000;83(1):17-21. doi:10.1007/s004210000255 PMID 11072768
  2. 02Tipton M. Extreme environmental physiology in the dock. Medico-Legal Journal. 2024;92(2):61-71. doi:10.1177/00258172231182601 PMID 38420761
  3. 03Tipton MJ. The Initial Responses to Cold-Water Immersion in Man. Clinical Science. 1989;77(6):581-588. doi:10.1042/cs0770581 PMID 2691172
  4. 04Tipton M, Barwood M, Eglin C, Massey H, Macleod R. ‘From lab to lifesaving’: the evolution of a public health campaign to reduce drownings. Injury Prevention. 2026;32(4):527-532. doi:10.1136/ip-2025-045970 PMID 41443990
  5. 05Shattock MJ, Tipton MJ. ‘Autonomic conflict’: a different way to die during cold water immersion?. The Journal of Physiology. 2012;590(14):3219-3230. doi:10.1113/jphysiol.2012.229864 PMID 22547634
  6. 06Lundström A, Karlsson M, Rydberg A, Wiklund U. Assessment of arrhythmias and heart rate response in healthy adolescents performing face immersion and body submersion in ice‐cold water. Physiological Reports. 2025;13(13):e70430. doi:10.14814/phy2.70430 PMID 40624837
  7. 07Barwood MJ, Eglin C, Hills SP, Johnston N, Massey H, McMorris T, et al.. Habituation of the cold shock response: A systematic review and meta-analysis. Journal of Thermal Biology. 2024;119:103775. doi:10.1016/j.jtherbio.2023.103775 PMID 38211547
  8. 08Eglin CM, Tipton MJ. Repeated cold showers as a method of habituating humans to the initial responses to cold water immersion. European Journal of Applied Physiology. 2005;93(5–6):624-629. doi:10.1007/s00421-004-1239-6 PMID 15778892
  9. 09Merkt B, Craviari C, Baggish AL, Namdar M, Meyer P. Cardiac arrhythmia during cold-water immersion: a self-controlled field study with extended rhythm monitoring. Journal of Exercise Science & Fitness. 2026;24(3):200479. doi:10.1016/j.jesf.2026.200479 PMID 42100593
  10. 10Tipton MJ, Golden FSC, Higenbottam C, Mekjavic IB, Eglin CM. Temperature dependence of habituation of the initial responses to cold-water immersion. European Journal of Applied Physiology. 1998;78(3):253-257. doi:10.1007/s004210050416 PMID 9721005
  11. 11US Centers for Disease Control and Prevention. Drowning Facts. US Centers for Disease Control and Prevention. 2026.
  12. 12Hills SP, Hobbs M, Tipton MJ, Barwood MJ. The water incident database (WAID) 2012 to 2019: a systematic evaluation of the documenting of UK drownings. BMC Public Health. 2021;21(1):1760. doi:10.1186/s12889-021-11827-0 PMID 34579685
  13. 13Baker AH, Jones A, Mayhew A, McAvoy C, Macleod R, Montgomery H, et al.. The physiology of survival: Breath‐hold shallow‐water diving. Experimental Physiology. 2026;111(5):2403-2410. doi:10.1113/EP093322
  14. 14Bizjak M, Košnik M, Dinevski D, Thomsen SF, Fomina D, Borzova E, et al.. Risk factors for systemic reactions in typical cold urticaria: Results from the COLD‐CE study. Allergy. 2022;77(7):2185-2199. doi:10.1111/all.15194 PMID 34862605
  15. 15Buijze GA, Sierevelt IN, van der Heijden BCJM, Dijkgraaf MG, Frings-Dresen MHW. The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial. PLOS ONE. 2016;11(9):e0161749. doi:10.1371/journal.pone.0161749 PMID 27631616
  16. 16Kelly JS, Davidson N, Delaney JP. Improved Mood Following Cold‐Water Immersion: A Comparison of Differing Exposure Durations. Lifestyle Medicine. 2026;7(2):e70048. doi:10.1002/lim2.70048
  17. 17Radtke T, Poerschke D, Wilhelm M, Trachsel LD, Tschanz H, Matter F, et al.. Acute effects of Finnish sauna and cold-water immersion on haemodynamic variables and autonomic nervous system activity in patients with heart failure. European Journal of Preventive Cardiology. 2016;23(6):593-601. doi:10.1177/2047487315594506 PMID 26152773
  18. 18Manolis AS, Manolis SA, Manolis AA, Manolis TA, Apostolaki N, Melita H. Winter Swimming: Body Hardening and Cardiorespiratory Protection Via Sustainable Acclimation. Current Sports Medicine Reports. 2019;18(11):401-415. doi:10.1249/JSR.0000000000000653 PMID 31702722