I used to hate the cold. Before starting Longevity Advice and learning about all the possible cryotherapy benefits for longevity, I was always the guy cranking the thermostat up to 80+° F, even during relatively mild fall weather.

My wife, whose body naturally runs hot and who loves the cold, waged a constant battle with me before bed to keep the temperature below 70° F for sleeping.

But now, I’m the first one to rush and turn the thermostat down to 66° F before going to bed, I wear t-shirts outside when shoveling snow, and I even (sometimes!) turn the shower all the way down to the coldest it can go, and spend my entire shower at that frigid temperature.

What caused such a dramatic turnaround in my relationship with the cold?

While I’m not quite as hardcore as “the ice man” Wim Hoff, famous for his “Wim Hoff method” for controlled breathing and ice baths, I discovered that cold therapy might actually be good for life extension.

But is cold exposure, specifically cryotherapy and cold water immersion, actually healthy, and could it lead to a longer, healthier life? Or will it just make your fingers and toes turn blue and fall off?

I decided to do a deep dive into the science behind cold plunges, whole-body cryotherapy, and cold showers, to look at the pros, the cons, and the risks.

Here’s what I learned.

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The science behind cryotherapy for longevity

Relative to other longevity interventions, like the Mediterranean diet, caloric restriction, and even supplements like resveratrol, cryotherapy is surprisingly understudied.

Most of the research on cold exposure benefits has been centered around its use by athletes to assist in muscle recovery and prevent muscle soreness post-workout. Much of the remaining research is low-quality observational studies (which, as I try to stress in every article, can only show correlation, not causation, as compared to the gold standard of a randomized controlled trial) with small numbers of test subjects, under wildly varying conditions. 

In fact, I was only able to find one decent meta-analysis for the entire cold therapy research field, which was not the case for all the other longevity topics I’ve looked into, where there are usually five or more quality meta-analyses from a range of different authors, publications, and time-periods.

And when you break down the different types of cold therapy—from cold water immersion (like ice baths) to whole-body cryotherapy (the kind done in a specialized chamber), to cold showers—you get even fewer studies for each sub-type.

This dearth of research about cryotherapy should probably make us skeptical about the outsized claims many prominent health influencers like Ben Greenfield, Andrew Huberman, and Rhonda Patrick make about cold therapy’s health benefits. I noticed practically none of them spend any time discussing the health risks of things like ice baths and cold water immersion which, from my reading of the literature (and the opinions of many doctors), are potentially very real and significant.

Luckily, however, this popularity of cold therapy for health among a slew of life extension influencers is leading to some newer, higher-quality research, which we’ll get into below.

And of course, several animal studies lend weight to the possible health benefits of cryotherapy for longevity.

Cryotherapy benefits for longevity

Animal studies suggesting the benefits of cold therapy break down into two categories: those showing general health benefits and those specifically showing longevity improvements. As with most life extension research, there are many more of the former than the latter.

For instance, a 2017 study of male rats suggested cold water swimming for 3 minutes at 39° F could help with recovery from traumatic brain injury: for the rats that underwent cold water immersion, “the number of CD34+ stem cells and new blood vessels in the injured hippocampus tissue increased significantly” compared to non-cold water treated rats.

A 2014 study of male mice found that cold exposure of “4° C [39° F] for one to eight hours three times a week” activated brown adipose tissue (also called brown fat: a mitochondria-rich form of fat considered “healthy” fat for its high energy-burning, inflammation-lowering properties) while increasing energy expenditure and improving glucose response.

There are only a couple animal studies that I could find showing specific longevity improvements from cold exposure.

A 1986 study of male rats suggested that immersion in cool water (73° F) for four hours a day, five days a week, resulted in fewer cancers, and a modest increase in average longevity of 45 days.

A 2012 study of female fruit flies showed a slight longevity increase in those exposed to mild cold.

While there are no direct, controlled trials of humans that show a longevity benefit to cold therapy (as with most longevity interventions; trying to run an 80+ year study is too resource and time-intensive), there are several showing some general health benefits.

I found one good meta-analysis from 2022 on cryotherapy benefits and cold water exposure results in humans. That analysis bemoaned the fact that, “Clear conclusions from most studies were hampered by the fact that they were carried out in small groups, often of one gender and with differences in exposure temperature and salt composition of the water.”

However, the authors did conclude that:

“[Cold Water Immersion] seems to reduce and/or transform body adipose tissue, as well as reduce insulin resistance and improve insulin sensitivity. This may have a protective effect against cardiovascular, obesity and other metabolic diseases and could have prophylactic health effects. Whether winter swimmers as a group are naturally healthier is unclear. Some of the studies indicate that voluntary exposure to cold water has some beneficial health effects. However, without further conclusive studies, the topic will continue to be a subject of debate.”

Luckily, as I mentioned above, all the attention on cryotherapy and cold stress for health has led to some promising new studies in humans.

A 2021 study in Cell of male winter swimmers suggested that they have higher brown fat activity and energy expenditure compared to those who don’t swim in cold water 2-3 times a week.

A 2022 meta analysis surveying ten different studies echoed this conclusion: “Acute cold exposure could improve the energy expenditure and [Brown Adipose Tissue] activity in adults, which is beneficial for humans against obesity.”

A 2021 study in the International Journal of Hyperthermia suggested, “whole-body short-term cold-water immersion (CWI; 14° C [57° F] for 10 min)” actually improved inflammation and immune response markers for up to 48 hours in men.

A 2016 study of women cold water swimmers found that cold therapy significantly increased insulin sensitivity.

A 2014 study found that men sleeping in colder temperatures (66° F) had more brown fat activation and better insulin responses to food.

Additionally, several studies on whole-body cryotherapy using specialized cryo chambers suggest it may lower oxidative stress, treat metabolic syndrome, and lower inflammation.

Finally, there is some research that cold therapy may benefit your mental health, as well (and, anecdotally, I can confirm this based on my own cold shower experiences).

A 2020 study on whole-body cryotherapy found that self-reported measures of depressive symptoms in adults improved with 10 sessions at up to -256 °F, while a 2004 study found that winter swimming improved the self-reported mood of the swimmers compared to controls.

How do the benefits of cold exposure vary by gender, age, and timing?

Referring again to the one good meta analysis on the subject, it seems that, “men tended to exhibit a greater metabolic response and shivering thermogenesis to [Cold Water Immersion], whereas women had a greater insulative response. The cooling rate was similar in both genders.”

This may mean it’s possible men could lose more body fat and potentially see more of the benefits of cold exposure than women. Additionally, it’s important to note that, as in most research, men have simply been more studied than women when it comes to cold therapy.

Regarding age, “A study exploring the difference in thermoregulatory response between old and young individuals observed a higher mean skin temperature in old subjects compared to the younger subjects. This suggests a deficit of thermoregulation, which may contribute to a loss in core temperature and development of hypothermia in older adults.” In other words, long cold exposure can be more dangerous for older adults as their bodies cannot maintain their core temperature as well as younger individuals. 

As for time of day, “there are no indications of circadian temperature rhythm affecting the thermoregulatory response to CWI in terms of shivering and vasoconstriction.”

But the benefits of cold exposure might be outweighed by some of the risks. As anyone who’s watched James Cameron’s Titanic can tell you, spending too much time in cold water (especially with a selfish girlfriend who won’t share her floating door), can lead to hypothermia and death.

Cold therapy risks

So what are the risks of cryotherapy and why might you want to avoid it if longevity is your goal?

Well, first of all, it might kill you.

A 2017 review article in Experimental Physiology notes that:

“In 2012, an estimated 372,000 people (42 per hour) died from immersion, assumed to be drowning… As a result of laboratory-based research, the initial responses to immersion, or ‘cold shock,’ were identified as particularly hazardous, accounting for the majority of immersion deaths.”

Basically, the “cold shock” response that so many health influencers love to talk about could be one of the leading causes of accidental death on the planet.

Basically, the “cold shock” response that so many health influencers love to talk about could be one of the leading causes of accidental death on the planet.

A great 2020 review of cold water swimming and ice baths notes, “there is a risk of death in unfamiliar people, either due to the initial neurogenic cold shock response or due to a progressive decrease in swimming efficiency or hypothermia.”

And the dangers of cold therapy don’t end there. The cold shock response may also increase cardiac troponin, a compound indicating heart muscle damage and myocardial lesions, according to one 2017 study.

People with heart diseases are more likely to experience heart rhythm disturbances during ice water baths, according to a 2009 study of 22 men.

Another 2012 review suggested, 

“Cold water submersion can induce a high incidence of cardiac arrhythmias in healthy volunteers… the ‘cold shock response’… may account for these arrhythmias and may, in some vulnerable individuals, be responsible for deaths that have previously wrongly been ascribed to drowning or hypothermia.”

A 2014 review found that, “the USA Triathlon Fatality Incidents Study reported that 79% of deaths in triathlons in the USA between 2003 and 2011 occurred during the swim, with unexplained sudden cardiac death, rather than hypothermia or hyperthermia, being the most likely cause of death in most cases.”

Cold water immersion could also lead to lung problems, like pulmonary edema.

Essentially, if you have (or suspect you have) an existing heart condition, cold water immersion and especially ice baths, is probably not a great idea. Certainly not without supervision.

But realistically, the main risk for most people is that cold therapy for longevity just might not work. 

As noted above, there really hasn’t been a lot of research into cold therapy, certainly compared to other longevity interventions like diet, and certainly not enough to justify the enthusiasm with which so many longevity influencers proselytize for it.

Animal studies on cryotherapy benefits have been mixed, with a 2015 paper on roundworms finding that, “although exposure to low temperatures at the adult stage prolongs lifespan, low-temperature treatment at the larval stage surprisingly reduces lifespan.”

Even the vaunted benefits of activating brown fat may not be so great for adults. A 2017 review observed:

“Indeed, the estimated contribution of BAT [Brown Adipose Tissue] to whole-body energy expenditure in cold-exposed adults is relatively small and has been suggested to be irrelevant to whole-body energy turnover and therefore obesity management… exposing people to severe and prolonged cold exposure may be impractical compared to the classic rodent model. Importantly, it is likely that longer bouts and more severe cold exposure may elicit a compensatory increase in appetite and food intake in humans, thus rendering the use of BAT activation inefficacious in the treatment of obesity”

And a 2012 study found that, “BAT thermogenesis in humans accounts for less than 20 kcal/day during moderate cold stress, even in subjects with relatively large BAT depots.” For context, 20 kcal is roughly equal to two minutes of moderately difficult jogging or two large strawberries.

There is one cold therapy risk you should not worry about, however: so-called “adrenal fatigue.” A 2016 meta analysis looked at 58 different studies and concluded, “there is no substantiation that “adrenal fatigue” is an actual medical condition.”

Ok, suppose you remain hyped about the possible benefits of cold therapy for longevity after all that. You’ve done the necessary medical tests to ensure you don’t have a risky heart condition, and you want to know how best to add cryotherapy or cold water immersion or ice plunges into your longevity routine. What does the research say about the best methods to reap the benefits of cold exposure?

Let’s find out.

How to do cold therapy for health and life extension

While there are some promising studies on whole-body cryotherapy, as noted above, most of the research into cold therapy has been around cold water immersion, either in ice tubs, cold plunges, or cold water swimming, so I’ll focus on water immersion in this section.

How cold does the water need to be?

The good news is you don’t have to literally be freezing to get the benefit of cold therapy for health.

Most studies I looked at had the water temperature between 50° F to 66° F (~10° C to 19° C). 

In fact, one study even noted you get no real additional benefit in terms of respiratory cold shock from going below about 50° F (10° C). Additionally, many of the risks of cold water immersion noted in a 2020 review happen in ice water, defined by the study as 41° F (5° C) or colder.

However, note that because water has a higher thermal conductivity than air, even relatively higher temperatures like 60° F will still feel colder than an equivalent temperature outside.

How long should I be in the water?

More good news! 

You can get a lot of benefits of cold exposure in just a few minutes.

The same study linked above observed: “Immersion in 10 °C [50 °F] water for only 2 min produces a large (2-fold) increase in plasma [norepinephrine] concentration.”

How often should I do cold water immersion therapy?

Several studies on cold water swimming and winter swimming showed positive effects from doing the activity 2-3 times per week.

And, actually, due to acclimation effects, where your body (and mind) get used to the cold exposure and it doesn’t elicit as much of a cold shock response, it may be best not to do cold water immersion every single day.

What time of day should I do cold therapy?

I’ll again quote my favorite cold therapy meta analysis: “there are no indications of circadian temperature rhythm affecting the thermoregulatory response to CWI in terms of shivering and vasoconstriction.”

That essentially means you should get much the same bodily response no matter what time of day you do a cold plunge.

That said, there is some nuance here regarding exercise days, especially if your goal is muscle growth (which, as we’ve covered before, is important in preventing sarcopenia in old age).

A 2015 study suggested that men who did cold water immersion right after a weight-lifting session gained less muscle than those who did not do cold therapy. 

Given that, it may be prudent to only do cold therapy on non-resistance training days, or to at least delay it for an hour or two after a workout if you really want to get swole.

What tools do I need for cold water immersion therapy?

As mentioned above, you really just need somewhat cold (50-66 °F) water and a container big enough to hold it and you for a few minutes, a few times a week.

Most of us already have this at home, and it’s called a bathtub.

A thermometer might not be a bad idea for the first few times as well, just to make sure you’re getting the temperature correct.

That said, for those of you simply aching for the hottest, newest gear, next week we’ll be “diving” (see what I did there?) into all the hippest cold plunge tubs, ice plunge barrels, and home cryotherapy products on the market.

Make sure to subscribe to get notified when that comparison article comes out!

Side note: Mapping your own brown fat

I was curious to see if there were easily accessible consumer tests so that spanners could measure their own brown fat levels, to see for themselves if cold therapy is really working for them specifically.

It seems like the two main methods to map brown fat used in research studies are MRIs and PET/CT scans. CT scans require the injection of radioactive sugar and just seem like a whole lot more work, frankly, and there are already lots of consumer MRI testing companies out there (we covered some of them when discussing how to detect cancer early).

So I called and emailed nine different private MRI providers but none of them currently offer a test to measure brown adipose tissue (BAT), though some are considering adding it after talking to me, and I will update here if they do!

I also called the DEXA Scan manufacturer but their scan is not able to differentiate between brown and white fat, just visceral vs. subcutaneous fat.

Anyone offering MRI tests to detect brown fat, send us an email! We’d love to work with you to offer that service to our readers.

How I personally plan to do cold therapy for longevity

When I first got into the longevity space and learned about cold therapy I got really fired up about it, and did cold showers practically every day for six months.

But my research for this article has actually thrown a little cold water (sorry!) onto that initial enthusiasm.

While, anecdotally, I feel energized, refreshed, and happy after a cold shower, and plan to continue them intermittently as I find I need a pick-me-up, I don’t think the current research really supports a more stringent habit than that. I won’t be forcing myself to stick to a strict weekly schedule, and I certainly won’t be pouring buckets of ice into my bathtub to achieve a sub-50° F temperature before hopping in.

That said, the research on sleep and temperature is interesting (and not just the study referenced above that showed sleeping at 66° F helps grow brown fat), so I will continue to sleep in colder temperatures. We’ll discuss all the research around that at length when we get into our article series on sleep and longevity (stay tuned!).

Do you disagree? Any big, important studies on the benefits of cryotherapy or cold therapy that I missed? 

Sound off in the comments below!