Most likely, you’ve seen at least a few cold-plunge enthusiasts on your social media feed by now — the kind who jump into holes cut into frozen lakes, for example, or invest in a chiller tub and insist it’s a boon for exercise recovery. But is there any evidence behind the trend?

A recent research review in PLOS ONE suggests that not only can these plunges assist with lowering inflammation related to exercise (rather than injury), they might actually have other benefits as well, including better sleep quality, lower stress, and stronger immunity.

Researchers looked at 11 studies that comprised 3,177 total participants. Cold-water interventions were performed in baths or showers that ranged from 5 to 15 degrees Celcius, with exposure durations from 20 seconds to two hours.

Although no effects on stress or immune function were shown immediately after a cold-water exposure, the studies found that both were improved within 24 to 48 hours afterward. For example, one study found that those who regularly take cold showers experienced a 29 percent reduction in sick days from work compared to those who didn’t have cold exposure.

A seemingly contradictory finding is that cold-water immersion causes a temporary increase in inflammation. However, the researchers noted that this brief spike is the body’s reaction to cold as a stressor and that it actually helps the body adapt and recover, similar to the way muscle damage from strength training makes muscles stronger.

How Cold Plunges Support Workout Recovery
Cold water immersion is exactly what it sounds like — getting into cold water, typically below 15 degrees, for a short period. Some people do quick plunges, while others stay in for a few minutes.

“The cold shock triggers a surge of norepinephrine, which can boost focus, energy, and stress resilience,” said Dr David Merrill, psychiatrist and neuroscientist, and director of the Pacific Brain Health Center at the Pacific Neuroscience Institute in Santa Monica, California. “It also activates the body’s natural recovery processes, reducing inflammation and improving circulation.”

Although he wasn’t part of the recent research, Merrill told Runner’s World the results were interesting because of the highlight on mental health benefits, which is not often covered in cold-plunge research or discussions.

“The idea is that cold exposure stimulates the nervous system in a way that helps regulate stress and the autonomic nervous system,” he said. “Right now, cold plunging seems to have more immediate, short-term benefits compared to long-term changes. People report feeling more awake, less anxious, and even euphoric right after a plunge, likely due to the rush of endorphins and adrenaline.”

The question is whether those effects translate into long-term improvements in mood and resilience, he noted. For that, we need studies that track people over time to see if regular cold exposure has lasting mental health benefits, especially for those with clinical depression or anxiety.

What to Know About Cold Plunge Research
Although the recent research suggests there are benefits to cold plunging, researchers did note that the studies assessed had limitations. Most notably, even though the combined number of participants across 11 studies added up to more than 3,000, most studies on the subject have small sample sizes, they stated. Also, there haven’t been enough randomised, controlled trials or studies with more diverse participant groups.

Because of that, we need more research, said Dr Tracy Zaslow,  primary care sports medicine specialist at Cedars-Sinai Orthopaedics in Los Angeles.

“The popularity of cold-water exposure has outpaced research into the subject,” she told Runner’s World. “Also, researchers haven’t determined an ideal amount of time to submerge or a preferred water temperature. Some studies are looking at freezing temperature. A lot of them are looking at 10 to 21 degrees, so the recommendations are all over the place.”

That doesn’t necessarily mean you should avoid the practice until there’s more research, she clarified, but it does imply that your results may not be as significant on an individual level as hoped.

If you do decide to incorporate cold plunges and see how they work for you, Zaslow recommends checking in with your health provider, especially if you have cardiovascular concerns.

“As with other health and fitness fads, ask your doctor first,” she said. “Risks associated with cold exposure include frostbite, hypothermia, heart arrhythmias and even heart attacks. It’s not a completely benign activity. Talk to your doctor to make sure that no harm comes from a fun activity that is intended to help your health.”

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