What the research says about cold plunges

There have been a number of studies on the potential health benefits of cold plunges. One systematic review, published in PLOS One in January, analyzed 11 studies to determine whether cold plunges were beneficial to health.

The researchers included only studies with cold-water immersion to chest level or higher and excluded studies where participants wore protective clothing. They also excluded studies that included "highly-trained and elite athletes competing at a national level or higher."

Ultimately, the researchers examined information from 3,177 participants and found that people who used cold plunges could experience a stress reduction for a limited time following exposure, have a decrease in sickness absences, and experience improvements in their quality of life and sleep.

However, the researchers also found that cold-water immersion increased inflammation immediately after and one hour post-exposure.

"At first glance, this seems contradictory, as we know that ice baths are regularly used by elite athletes to reduce inflammation and muscle soreness after exercise," said study coauthor Ben Singh in a press release. "The immediate spike in inflammation is the body's reaction to the cold as a stressor. It helps the body adapt and recover and is similar to how exercise causes muscle damage before making muscles stronger, which is why athletes use it despite the short-term increase."

"[K]nowing this, people with preexisting health conditions should take extra care if participating in cold-water immersion experiences, as the initial inflammation could have detrimental health impacts," Singh said.

Tara Cain, project manager for Dialling Up Health and an author on the study, explained that there could still be long-term positive effects for cold plunges.

"The body perceives cold as a stressor, activating an immune response that temporarily increases inflammation, much like how exercise causes short-term muscle damage before leading to strength gains," Cain said. "Over time, regular use of cold-water immersion may help reduce overall inflammation and support recovery, which is why it remains popular among athletes despite the initial inflammatory response."

Other research has found health benefits to cold plunges as well. In one review published in 2016, researchers found that several studies suggested cold plunging or cold-water therapy could increase blood flow, reduce heart rate, and improve overall cardiovascular health. That review also found that cold plunges could have beneficial effects on metabolism and body fat, including reducing the risk of metabolic diseases and reducing body fat.

Other research has suggested that cold plunges can temporarily lead to a mood boost that could extend to long-term mental health benefits, including reduced anxiety and depression.

Mark Harper, a physician and regular cold-water swimmer, said there are strong signs people can derive mental health benefits from cold plunging.

Harper noted that the positive effects he's observed of cold-water immersion could be the result of the placebo effect. For example, the benefits of cold-water immersion could come from meeting people, the exercise itself, or the simple act of accepting a challenge and completing it, which can improve self-confidence, Harper said.

They ultimately found that the practice can present some dangers. Deaths from cold-water immersion do happen, as the shock of the cold water can cause people to hyperventilate and drown. However, Tipton said the risks can be managed with some common sense and precautions.

For example, you don't need to dive into extreme temperatures for potential benefits. Entering the water at a temperature of 15 to 20 degrees Celsius (or 59 to 68 degrees Fahrenheit) and staying only for a few minutes is sufficient.

Tipton said if the water is colder than that, you might get more benefit, but you should limit your exposure.

"If you ask me what protocol you would follow if you thought this was going to be doing you good, I wouldn't go in water much below 12C (54F), and I wouldn't stay in for much more than two minutes," he said.

Of note, a 2016 review on cold showering found there was no difference between 30, 60, or 90 seconds of exposure, and that the benefits seemed to plateau after around 30 seconds.

"People think it's got to be super cold, super long, and the longer the better, and that's wrong," Harper said.

Tipton cautioned against spending a long time in an ice bath. "Sitting in water for as long as I can fills me with horror," he said. "This could destroy small nerves, blood vessels in extremities, and could result in amputation the same way frostbite can."

Tipton also suggested overall caution and a medical screening if you decide to try out a cold plunge. He said humans are considered "tropical animals" who need to adapt to the cold and are better suited to warmer environments.

The resting body temperature of a human is around 36.5 to 37.5 degrees Celsius (or 97.7 to 99.5 degrees Fahrenheit). As a result, cold-water immersion can be stressful and carries risks for the cardiovascular and respiratory systems.

"We don't want to stop people doing it, but we want to make sure they do it in a way that maximizes the benefits and minimizes the risks," Tipton said.