Celebrities love cold plunges. But are they actually good for you?

Earlier this month Dune 2 star Josh Brolin stripped down to boxers during his Saturday Night Live monologue to hop into an ice bath on stage. He told the audience he's "been doing cold plunges for 20 years" and likened the experience to SNL hosting duties. "It’s scary, it’s exhilarating," he said. "There’s just no way to prepare for it. So what you gotta do is just jump right in. Surender to the discomfort!"

Brolin isn't the only celebrity who's a fan of submerging himself into ice-cold water. Actor and director Bradley Cooper recently revealed to the New York Times that he does a cold plunge “every morning when I get up.” According to the publication, the Maestro and Hangover star — pictured floating in a creek on a snowy day wearing nothing but shorts — likes to “meditate in freezing temperatures.”

For years celebrities and athletes alike, including Justin Bieber, have been talking about using cold water immersion to boost muscle recovery. The Wim Hof Method, created by Dutch extreme athlete Wim Hof, has also popularized cold therapy, which he claims heightens focus, increases energy and reduces stress levels.

The practice has become more mainstream, as social media has shown people even purchasing ice baths for their backyards to incorporate a plunge into their daily routines. Some spas and workout studios also have cold plunges to their offerings.

But does the growing access to ice baths mean that more people should be participating in the plunge? Here's what experts think — and what a new study finds.

What is cold plunging, and why are people doing it?

Cold plunging is a practice of cold therapy that involves total or partial immersion into water that is below 60 degrees Fahrenheit for a short period of time. Andrew Jagim, director of sports medicine research at the Mayo Clinic Health System, tells Yahoo Life that immersion can be continuous or done in multiple intermittent sessions. Most people start at 30 seconds.

“It’s common practice among athletes or fitness enthusiasts to either start the day with a cold plunge or follow a workout or training session with a cold plunge, with the intent of improving recovery,” he says.

Cold plunging is said to improve muscle recovery by inducing what Jagim refers to as “a state of vasoconstriction, in which the blood vessels rapidly constrict to redirect blood flow to central organs.” In doing so, it can limit inflammation in muscles post-exercise.

However, it’s not just people doing intense physical activity who are participating in cold immersion therapy. Jagim says he’s seen claims that cold plunging has helped treat symptoms of chronic pain or resulted in “improvements in mood and bolstered resilience to stress, which can aid in immune system functioning.”

While people across the internet have listed these potential benefits as fact, experts admit that there’s limited research to back them up. François Haman, a health science professor at the University of Ottawa in Canada who has studied cold exposure for two decades, is among them.

“Assuming that cold improves inflammation, cold improves the immune system, that’s totally unclear,” he tells Yahoo Life. “Measuring changes in the immune system is actually not that easy.”

Although it’s “not demonstrated scientifically,” he does concede the importance of anecdotal evidence. “There is some indication that pain can actually be improved. ... People feel better,” he says.

What Haman knows to be true is that cold water immersion is a stimulant that acts like any other stimulant. “You experience very high stress initially and that is extremely stimulating, so you’re gonna get a dopamine release, you’re gonna get noradrenaline being released,” he explains. “So basically stress hormones go up, and when you come out of it, it’s almost like giving you new life. You feel super-activated.”

Haman says the effects on the mind are also clear. “When you hit that cool water, you can find a way to basically go into a meditative state,” he says. “You’re facing a very strenuous type of stress and learning to keep control of your body. So there’s evidence that it does improve that capacity to set a different mindset and to be able to learn about meditation, learn about [mindfulness], all these things.”

These benefits are a result of doing cold water immersion for up to two minutes. Staying in cold water for longer than that, however, comes with certain risks. “When you say two minutes is good, people will think ‘20 minutes is 10 times better,’” Haman says. “That’s not the way it works.”

What the research says

An analysis of eight trials conducted on the Wim Hof Method (WHM) was published March 13 in the journal PLOS One. The extreme athlete credits his ability to withstand the cold to his training method focused on practicing cold water therapy with a specific form of breathing. But this new review concludes that the quality of the research available is inadequate to support the wellness claims Hof makes.

According to researchers, past studies have involved small sample sizes and a high risk of bias (86.4% of participants have been male, for example), which may skew their results. The review also reports that psychological outcomes for participants were difficult to measure, noting that those trying the WHM might be simply be experiencing a placebo effect.

Some research supports potential anti-inflammatory and immune-related effects of cold water immersion paired with the breathing method. However, the studies weren't able to determine which piece of the practice contributed to that benefit, whether it be the breathing, meditation or the cold exposure itself.

"Studies about WHM have not yet investigated all the beneficial claims the WHM states to have," the report reads. "There is still much to explore."

Is cold plunging safe?

Immersing yourself into cold water is “a calculated risk” at all times, according to Haman, because of the potential for hypothermia, skin damage, cardiac stress, increased blood pressure and even drowning. The lack of regulation around the practice makes people more vulnerable.

“Assuming that everybody responds the same way to cold is extremely dangerous,” he says. “I’ve had some people have a lot of difficulties in the cold; other people had no issues.”

He likens it to practicing any strenuous physical activity, noting that certain precautions should be taken to ensure that somebody is physically fit and able to sustain a cold plunge. Without information about a person’s health or injuries, it can become life-threatening, as the National Center for Cold Water Safety warns on its website.

“Certain individuals with chronic health conditions such as cardiovascular disease or autoimmune conditions affecting blood flow ... may want to consult their primary care physician prior to engaging in cold plunging to minimize risks of adverse reactions,” says Jagim.

Haman recommends a number of precautions for those interested in trying a cold plunge, from doing it in water that is only waist-deep to ensure you can get out safely, to participating with a partner or in a group, to covering the hands and feet to avoid injuries. He also reiterates a two-minute time limit.

“Two minutes is enough to create the cold shock response, to regain control, do a minute of deep meditation and then you get out,” Haman says. “That’s the safe way of doing it. People that do it regularly may want to push a little bit. But the longer you stay in, the more dangerous it becomes.”

And if a full cold plunge isn’t your thing, he advises that a cold shower every once in a while can provide many of the same benefits.

“I’m not in the business of preventing people from doing a cold plunge,” he says, “I’m in the business of making sure people do it in a safe manner, and do it well.”

This article was originally published on Feb. 21, 2024 and has been updated.