Story · Cold

Most cold plunge rules come from studies that kept people cold for hours.

Cold plunge advice keeps repeating a few famous numbers, like a 250% jump in dopamine and 11 minutes a week. We traced each one back to the study it came from, then plotted every study by how cold it got and how long each session lasted.

By Adam BognarSep 24, 20268 min read

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Cold waterCold showerCold roomCooling suit or blanket

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Every shape on this map is a cold study

Lower on the map means colder. Session length runs left to right on a stretched scale, so twenty seconds and six hours both fit.

Blue circles are studies that put people in water, and the one triangle is a trial of cold showers. People spent hours at a time in the cold rooms and cooling suits behind the pale squares and diamonds. The orange band marks the one to five minutes per session that the Huberman Lab newsletter recommends.Source 1 · PodcastThe Science & Use of Cold Exposure for Health & PerformanceHuberman Lab. Huberman Lab Neural Network newsletter, 2022.Read the page ↗

Rule one says cold boosts dopamine

The 250% dopamine figure came from an hour at 14°C

In a Prague lab, ten young men sat up to the neck in 14°C water for a full hour. The dopamine in their blood rose 250%. Their metabolic rate climbed 350%, and the stress hormone noradrenaline jumped 530%.Source 2 · Clinical trialHuman physiological responses to immersion into water of different temperaturesŠrámek P, Šimečková M, Janský L, et al.. European Journal of Applied Physiology, 2000.Read the paper ↗PubMed ↗

Andrew Huberman walked through those numbers in a 2022 podcast episode on cold.Source 3 · PodcastUsing Deliberate Cold Exposure for Health and Performance (episode 66)Huberman A. Huberman Lab podcast, 2022.Read the page ↗ The same lab had run the same hour at 14°C a few years earlier, and dopamine didn't rise significantly that time.Source 4 · Clinical trialChange in sympathetic activity, cardiovascular functions and plasma hormone concentrations due to cold water immersion in menJanský L, Šrámek P, Šavlíková J, et al.. European Journal of Applied Physiology and Occupational Physiology, 1996.Read the paper ↗PubMed ↗

Rule one continues

Both studies measured dopamine in the blood

Blood dopamine comes mostly from nerves around the body and from the gut,Source 5 · Clinical trialNeuronal Source of Plasma DopamineGoldstein DS, Holmes C. Clinical Chemistry, 2008.Read the paper ↗PubMed ↗Source 6 · Clinical trialSources and Physiological Significance of Plasma Dopamine SulfateGoldstein DS, Swoboda KJ, Miles JM, et al.. The Journal of Clinical Endocrinology & Metabolism, 1999.Read the paper ↗PubMed ↗ and very little of what circulates gets into most of the brain.Source 7 · ReviewCatecholamine metabolism revisited: from neurochemistry to integrative physiology and pathophysiologyGoldstein DS, Eisenhofer G. Physiological Reviews, 2026.Read the paper ↗PubMed ↗

Among studies with hormone data, the closest match to a home plunge is a 2025 German study. In that study, five minutes at 8 to 12°C more than doubled noradrenaline, but the researchers didn't measure dopamine.Source 8 · Crossover trialEffects of time-of-day on the noradrenaline, adrenaline, cortisol and blood lipidome response to an ice bathBraunsperger A, Bauer M, Brahim CB, et al.. Scientific Reports, 2025.Read the paper ↗PubMed ↗

By 2026 a plunge maker's blog was claiming cold water can push dopamine up to 500 times above normal, and a syndicated news story repeated it.Source 9 · News reportCold Plunges Spike Dopamine Up to 500x and Rewire Your BrainAgate S. Kansas City Star, syndicated on Yahoo Health, 2026.Read the page ↗

Rule two asks for 11 minutes a week

The 11 minutes came from what seven swimmers said they did

A 2021 Danish study compared seven young men who swam through the winter with eight who didn't. Its first table lists the swimmers' own habits. On average they swam about 2.6 times and logged 11 minutes of cold water each week.Source 10 · Cross-sectional studyAltered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming menSøberg S, Löfgren J, Philipsen FE, et al.. Cell Reports Medicine, 2021.Read the paper ↗PubMed ↗

The researchers never assigned 11 minutes or tested any other amount. In the lab, the cold came from water-cooled blankets, and each man lay under them for more than three hours.Source 10 · Cross-sectional studyAltered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming menSøberg S, Löfgren J, Philipsen FE, et al.. Cell Reports Medicine, 2021.Read the paper ↗PubMed ↗

The newsletter turned that habit into a target. It says to aim for 11 minutes a week across two to four sessions of one to five minutes each.Source 1 · PodcastThe Science & Use of Cold Exposure for Health & PerformanceHuberman Lab. Huberman Lab Neural Network newsletter, 2022.Read the page ↗

Rule three wants you to end on cold

The rule named after Søberg never appears in her paper

The idea is to let your body rewarm by itself afterward. In his 2022 episode, Huberman named it the Søberg principle after the study's first author.Source 3 · PodcastUsing Deliberate Cold Exposure for Health and Performance (episode 66)Huberman A. Huberman Lab podcast, 2022.Read the page ↗ Her 2021 paper never mentions finishing on cold or tests which order works better.Source 10 · Cross-sectional studyAltered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming menSøberg S, Löfgren J, Philipsen FE, et al.. Cell Reports Medicine, 2021.Read the paper ↗PubMed ↗

We couldn't find a human trial that tests the order. The closest one added a 90-second lake dip to each break between two sauna rounds. The dips kept core temperature lower and made the second round easier to bear. That trial measured nothing about fat.Source 11 · Crossover trialThermal and cardiovascular responses to sauna are attenuated by adding cold water immersion to cooling breaksOwen TF, Giles CJ, Leaney SF, et al.. Experimental Physiology, 2026.Read the paper ↗PubMed ↗ Watch that session minute by minute.

Cold is said to help blood sugar

The insulin result took six hours a day in a cold room

Eight men with type 2 diabetes sat in a 14 to 15°C room in shorts and a T-shirt for six hours a day. After ten days their insulin sensitivity was up about 43%.Source 12 · Clinical trialShort-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitusHanssen MJW, Hoeks J, Brans B, et al.. Nature Medicine, 2015.Read the paper ↗PubMed ↗

A follow-up trial from the same group ran the schedule at 16 to 17°C and found no improvement. People shivered far less that time. The authors suspect the muscles need to do some shivering for the effect to appear.Source 13 · Clinical trialMetabolic responses to mild cold acclimation in type 2 diabetes patientsRemie CME, Moonen MPB, Roumans KHM, et al.. Nature Communications, 2021.Read the paper ↗PubMed ↗

Cold gets sold as a fat burner

Hours of cold a day grew brown fat by a third or more

Brown fat burns energy to make heat. In a Dutch study, 17 young adults spent ten days in a 15 to 16°C room, most days for six hours. Their brown fat grew by more than a third, and their weight and body composition stayed the same.Source 14 · Clinical trialCold acclimation recruits human brown fat and increases nonshivering thermogenesisvan der Lans AA, Hoeks J, Brans B, et al.. Journal of Clinical Investigation, 2013.Read the paper ↗PubMed ↗ In six men who wore a 10°C cooling suit for two hours a day, active brown fat grew 45% in four weeks.Source 15 · Clinical trialIncreased Brown Adipose Tissue Oxidative Capacity in Cold-Acclimated HumansBlondin DP, Labbé SM, Tingelstad HC, et al.. The Journal of Clinical Endocrinology & Metabolism, 2014.Read the paper ↗PubMed ↗

Japanese men who started with little brown fat lost 0.7 kg of fat after six weeks of two hours a day at 17°C.Source 16 · Randomized trialRecruited brown adipose tissue as an antiobesity agent in humansYoneshiro T, Aita S, Matsushita M, et al.. Journal of Clinical Investigation, 2013.Read the paper ↗PubMed ↗

Cold water can make you hungrier, too. After 30 minutes in 16°C water, people ate about 231 kcal more at the next meal than they did after warm water.Source 17 · Crossover trialEffects of cold-water immersion on energy expenditure, ad-libitum energy intake and appetite in healthy adultsGrigg MJ, Thake CD, Allgrove JE, et al.. Physiology & Behavior, 2025.Read the paper ↗PubMed ↗

The rush gets measured

Short, very cold dips raise noradrenaline two- to threefold

Ten Finnish women dipped for 20 seconds in 0 to 2°C water three times a week. For all 12 weeks, their noradrenaline rose two- to threefold after every swim.Source 18 · Clinical trialEffects of long‐term whole‐body cold exposures on plasma concentrations of ACTH, beta‐endorphin, cortisol, catecholamines and cytokines in healthy femalesLeppäluoto J, Westerlund T, Huttunen P, et al.. Scandinavian Journal of Clinical and Laboratory Investigation, 2008.Read the paper ↗PubMed ↗

Five minutes at 8 to 12°C raised it by 127% to 144% in the German study.Source 8 · Crossover trialEffects of time-of-day on the noradrenaline, adrenaline, cortisol and blood lipidome response to an ice bathBraunsperger A, Bauer M, Brahim CB, et al.. Scientific Reports, 2025.Read the paper ↗PubMed ↗ In Finnish winter swimmers, the rise after each dip shrank over three months of regular swimming.Source 19 · Cohort studyEffect of Regular Winter Swimming on the Activity of the Sympathoadrenal System Before and After a Single Cold Water ImmersionHuttunen P, Rintamäki H, Hirvonen J. International Journal of Circumpolar Health, 2001.Read the paper ↗PubMed ↗

Sore muscles come next

Ice baths trim soreness and can blunt muscle growth

A pooled analysis of nine small trials found that ice baths after hard exercise cut soreness by about 0.3 points on a scale of 0 to 10.Source 20 · Meta-analysisCan Water Temperature and Immersion Time Influence the Effect of Cold Water Immersion on Muscle Soreness? A Systematic Review and Meta-AnalysisMachado AF, Ferreira PH, Micheletti JK, et al.. Sports Medicine, 2016.Read the paper ↗PubMed ↗ The dashed box covers the water temperatures and times those trials used.

Men who sat in 10°C water for ten minutes after every leg session for 12 weeks added 103 g of quadriceps muscle. That's about a third of what men who cooled down with an easy bike ride put on.Source 21 · Randomized trialPost‐exercise cold water immersion attenuates acute anabolic signalling and long‐term adaptations in muscle to strength trainingRoberts LA, Raastad T, Markworth JF, et al.. The Journal of Physiology, 2015.Read the paper ↗PubMed ↗

Short doses get their turn

Thirty seconds of cold did as much as ninety

A Dutch trial asked 3,018 people to finish their hot shower with 30 to 90 seconds of cold every day for a month. They took 29% fewer sick days off work, and the length of the cold made no difference. The number of days they felt ill didn't change significantly.Source 22 · 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 ↗

Students with low mood felt about as much better after 5 minutes in 13.6°C sea water as after 20.Source 23 · Randomized trialImproved Mood Following Cold‐Water Immersion: A Comparison of Differing Exposure DurationsKelly JS, Davidson N, Delaney JP. Lifestyle Medicine, 2026.Read the paper ↗ A study of 5 minutes at 20°C also found mood lifting straight afterward, but it had no comparison group.Source 24 · Clinical trialShort-Term Head-Out Whole-Body Cold-Water Immersion Facilitates Positive Affect and Increases Interaction between Large-Scale Brain NetworksYankouskaya A, Williamson R, Stacey C, et al.. Biology, 2023.Read the paper ↗PubMed ↗

Now it's your turn

Drop your own plunge onto the map

Set the water temperature and how long you usually stay in. The map marks your plunge and names the three studies nearest to it.

Cold waterCold showerCold roomCooling suit or blanket

Water temperature 10°CTime in the water 3 minutes

These studies come closest to your plunge

Braunsperger 2025 · 5 minutes at 8–12°CNoradrenaline rose 127% to 144%. Dopamine was not measured.
Kelly 2026 · 5 minutes in a 13.6°C seaMood disturbance scores fell 14.7 points. Twenty minutes in the water did about the same.
Buijze 2016 · 30–90 seconds of cold to end a hot showerSick days off work fell 29%. Days of feeling ill did not change.

The first minute carries the most risk

Cold water sets off a gasp and fast breathing in the first minute. Men new to 10°C water averaged 47 breaths a minute in their first 30 seconds.Source 25 · 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 ↗ In lab studies, young and fit volunteers held their breath and went under cold water. Irregular heartbeats showed up in 62% to 82% of those submersions.Source 26 · 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 ↗

Keep your face out of the water, and have someone nearby when you plunge. Read how cold shock works.

This story touches these claims

74°H

Stretched

Cold

“A cold plunge raises your dopamine by 250%.”

89°H

Hot air

Cold

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

92°H

Hot air

Cold

“End your sauna session on cold to burn more fat.”

72°H

Stretched

Cold

“Cold plunges burn fat by switching on brown fat.”

62°H

Stretched

Cold

“Cold exposure improves insulin sensitivity by 43%.”

30°H

Likely

Cold

“Ice baths help you recover faster after exercise.”

22°H

Likely

Cold

“Ice baths after lifting weights blunt your muscle gains.”

50°H

Unsettled

Cold

“Cold showers mean you get sick less.”

We placed each study from its own methods section

We placed each shape at the temperature and session length its paper reports. For cooling suits and blankets we used the temperature of the water running through them. Bars show a range where a study gave one, and the dashed box spans the trials pooled in the Machado review.Source 20 · Meta-analysisCan Water Temperature and Immersion Time Influence the Effect of Cold Water Immersion on Muscle Soreness? A Systematic Review and Meta-AnalysisMachado AF, Ferreira PH, Micheletti JK, et al.. Sports Medicine, 2016.Read the paper ↗PubMed ↗

Janský's 1996 study used the same hour at 14°C as Šrámek's, so we drew it slightly colder and longer to keep both visible. The Søberg point goes in the middle of the 2 to 24°C range its blankets ran through.Source 10 · Cross-sectional studyAltered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming menSøberg S, Löfgren J, Philipsen FE, et al.. Cell Reports Medicine, 2021.Read the paper ↗PubMed ↗ When you drop in your own plunge, we rank studies by their distance from it on the map. A tenfold change in minutes counts about as much as 18°C.