Cold Plunges May Temporarily Reduce Stress, Improve Sleep

• A new study found that cold-water immersion offers several potential short-term health benefits.
• People had reduced stress levels in the 12 hours after doing cold-water immersion.
• Brief cold showers were associated with a slightly higher quality of life.

Cold-water immersion — such as sitting in an ice bath, wading into a lake in the winter, or taking a cold shower — has become increasingly popular in recent years. But is there any benefit to these bone-chilling practices?

New research suggests yes, with possible benefits ranging from lower stress to improved sleep and quality of life.

However, researchers caution that some of the benefits are short-term and depend on who is performing the cold therapy and what method they are using.

“Cold-water immersion has been extensively researched and used in sporting contexts to help athletes recover, but despite its growing popularity among health and wellbeing circles, little is known about its effects on the general population,” said study author Tara Cain, a researcher at University of South Australia (UniSA), in a press statement.

The new paper, published January 29 in PLoS One, carried out a comprehensive systematic review and meta-analysis of 11 previous studies involving 3,177 healthy adult participants.

In those studies, participants were immersed in water at or above chest level for 30 seconds up to two hours, with water temperatures ranging from 7°C to 15°C (45°F to 59°F).

Researchers focused on the following outcomes:

Their analysis showed a range of time-dependent results. For example, cold-water immersion reduced stress levels only during the 12 hours after people were exposed to the cold.

In addition, people who took 30-, 60- or 90-second cold showers for 30 days reported a slightly higher quality of life. But these effects faded after three months.

“Benefits may be gained from cold showers as well,” Cain said in the statement, “with one study reporting that participants who took regular cold showers experiencing a 29% reduction in sickness absence.”

“We also found some links to cold-water immersion and better sleep outcomes,” she continued, “but the data was restricted to males, so its broader application is limited.”

As for the benefits of cold-water immersion for boosting immunity and mood, researchers “found little evidence to support these claims,” Cain said.

The researchers also found that cold-water immersion was linked to a temporary increase in inflammation right after 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,” study author Ben Singh, PhD, also of UniSA, said in the 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,” he said.

“Knowing this, people with pre-existing health conditions should take extra care if participating in cold-water immersion experiences, as the initial inflammation could have detrimental health impacts,” Singh added.

Other research, including a study of the Wim Hof method, which combines breathing exercises with cold water immersion, has shown similar physical and mental health benefits of cold water therapy.

A spokesperson for the Wim Hof Method told Healthline they are not planning on releasing a statement about the new paper at this time.

Although the new paper showed the possible benefits of cold-water immersion, the studies reviewed by researchers had several limitations, including variations in how they were carried out.

The researchers wrote in the paper that some studies only looked at the effect of a single cold-water immersion, which limits the ability to make conclusions about long-term benefits.

Only one study included female participants, limiting applicability across the general population. Furthermore, most of the studies were conducted with a small number of participants.

“Right now, there isn’t enough high-quality research to say exactly who benefits most or what the ideal approach is to cold-water immersion,” Cain said. “More long-term studies, among more diverse populations, are needed to understand its lasting effects and practical applications.”

“Cold-water immersion has been used in athletics for a while,” said Steven Malin, PhD, associate professor in the Department of Kinesiology and Health at Rutgers-New Brunswick School of Arts and Sciences.

“So it’s a good approach, potentially, for some people, when needing to reduce inflammation and manage muscle soreness,” he told Healthline. “It can be a good rehabilitative tool to help athletes or people recovering from certain events.”

He said cold-water immersion aligns with the RICE (rest, ice, compression, elevation) protocol for caring for musculoskeletal injuries, with ice being a “critical part” of that because it reduces inflammation.

“Ice itself can actually impair the synthesis process for growing muscle,” Malin said, “so if it’s used repetitively, it could be a hindrance to gaining muscle.”

As for the annual Polar Bear Plunges that are popular around the start of the new year, Malin said these may not be done therapeutically but can still offer psychological and social benefits.

“Cold plunges are a matter of resilience and building a level of tolerance toward discomfort and being able to work through that,” he said. “There’s also the social aspect — just being with other people.”

So, should everyone rush out to buy an ice tub for their home? Malin doesn’t think so.

“I consider [cold-water immersion] as more of a single tool in a toolbox of lifestyle behaviors,” he said. “Occasionally doing cold therapy probably won’t be a problem for most people.”

“I don’t think people should feel left out if they don’t want to do cold therapy,” he said. “Exposure to cold itself can actually be harmful, particularly for people with underlying vascular disease like high blood pressure.”

For people with existing health conditions, Malin recommends they talk with a healthcare professional before trying cold-water immersion or other types of cold therapy.

Researchers carried out a systematic review and meta-analysis of 11 previous studies examining the benefits of cold-water immersion, with a total of 3,177 healthy adult participants.

They found that cold-water immersion was associated with reduced stress levels, a slightly higher quality of life, and better sleep outcomes. Little evidence was found of cold-water immersion boosting immunity and mood.

The previous studies had several limitations, including variations in how they were carried out, including some studies looking at single immersions, the lack of a diverse group of participants, and many studies having a small number of participants.