The coolest thing on social media these days may be celebrities and regular folks plunging into frigid water or taking ice baths.

The touted benefits include improved mood, more energy, weight loss and reduced inflammation, but the science supporting some of those claims is lukewarm.

Kim Kardashian posted her foray on Instagram. Harry Styles has tweeted about his dips. Kristen Bell says her plunges are 香蕉视频直播渂rutal香蕉视频直播� but mentally uplifting. And Lizzo claims ice plunges reduce inflammation and make her body feel better.

Here香蕉视频直播檚 what medical evidence, experts and fans say about the practice, which dates back centuries.

THE MIND

You might call Dan O香蕉视频直播機onor an amateur authority on cold water immersion. Since June 2020, the 55-year-old Chicago man has plunged into Lake Michigan almost daily, including on frigid winter mornings when he has to shovel through the ice.

香蕉视频直播淭he endorphin rush 香蕉视频直播� is an incredible way to wake up and just kind of shock the body and get the engine going,香蕉视频直播� O香蕉视频直播機onor said on a recent morning when the air temperature was a frosty 23 degrees (minus-5 Celsius). Endorphins are 香蕉视频直播渇eel good香蕉视频直播� hormones released in response to pain, stress, exercise and other activities.

With the lake temperature 34 degrees (1 Celsius), the bare-chested O香蕉视频直播機onor did a running jump from the snow-covered shore to launch a forward flip into the icy gray water.

His first plunge came early in the pandemic, when he went on a bourbon bender and his annoyed wife told him to 香蕉视频直播済o jump in the lake.香蕉视频直播� The water felt good that June day. The world was in a coronavirus funk, O香蕉视频直播機onor says, and that made him want to continue. As the water grew colder with the seasons, the psychological effect was even greater, he said.

香蕉视频直播淢y mental health is a lot stronger, a lot brighter. I found some Zen down here coming down and jumping into the lake and shocking that body,香蕉视频直播� O香蕉视频直播機onor said.

Dr. Will Cronenwett, chief of psychiatry at Northwestern University香蕉视频直播檚 Feinberg medical school, tried cold-water immersion once, years ago while visiting Scandinavian friends on a Baltic island. After a sauna, he jumped into the ice-cold water for a few minutes and had what he called an intense and invigorating experience.

香蕉视频直播淚t felt like I was being stabbed with hundreds of millions of really small electrical needles,香蕉视频直播� he said. 香蕉视频直播淚 felt like I was strong and powerful and could do anything.香蕉视频直播�

But Cronenwett says studying cold water immersion with a gold-standard randomized controlled trial is challenging because devising a placebo for cold plunges could be difficult.

There are a few theories on how it affects the psyche.

Cronenwett says cold water immersion stimulates the part of the nervous system that controls the resting or relaxation state. That may enhance feelings of well-being.

It also stimulates the part of the nervous system that regulates fight-or-flight stress response. Doing it on a regular basis may dampen that response, which could in turn help people feel better able to handle other stresses in their lives, although that is not proven, he said.

香蕉视频直播淵ou have to conquer your own trepidation. You have to muster the courage to do it,香蕉视频直播� he said. 香蕉视频直播淎nd when you finally do it, you feel like you香蕉视频直播檝e accomplished something meaningful. You香蕉视频直播檝e achieved a goal.香蕉视频直播�

Czech researchers found that cold water plunging can increase blood concentrations of dopamine 香蕉视频直播� another so-called happy hormone made in the brain 香蕉视频直播� by 250%. High amounts have been linked with paranoia and aggression, noted physiologist James Mercer, a professor emeritus at the Arctic University of Norway who co-authored a recent scientific review of cold water immersion studies.

THE HEART

Cold water immersion raises blood pressure and increases stress on the heart. Studies have shown this is safe for healthy people and the effects are only temporary.

But it can be dangerous for people with heart trouble, sometimes leading to life-threatening irregular heartbeats, Cronenwett said. People with heart conditions or a family history of early heart disease should consult a physician before plunging, he said.

METABOLISM

Repeated cold-water immersions during winter months have been shown to improve how the body responds to insulin, a hormone that controls blood sugar levels, Mercer noted. This might help reduce risks for diabetes or keep the disease under better control in people already affected, although more studies are needed to prove that.

Cold water immersion also activates brown fat 香蕉视频直播� tissue that helps keep the body warm and helps it control blood sugar and insulin levels. It also helps the body burn calories, which has prompted research into whether cold water immersion is an effective way to lose weight. The evidence so far is inconclusive.

IMMUNE SYSTEM

Anecdotal research suggests that people who routinely swim in chilly water get fewer colds, and there香蕉视频直播檚 evidence that it can increase levels of certain white blood cells and other infection-fighting substances. Whether an occasional dunk in ice water can produce the same effect is unclear.

Among the biggest unanswered questions: How cold does water have to be to achieve any health benefits? And will a quick dunk have the same effect as a long swim?

香蕉视频直播淭here is no answer to `the colder the better,香蕉视频直播澫憬妒悠抵辈�� Mercer said. 香蕉视频直播淎lso, it depends on the type of response you are looking at. For example, some occur very quickly, like changes in blood pressure. 香蕉视频直播� Others, such as the formation of brown fat, take much longer.香蕉视频直播�

O香蕉视频直播機onor plunges year-round, but he says winter dunks are the best for 香蕉视频直播渕ental clarity,香蕉视频直播� even if they sometimes last only 30 seconds.

On those icy mornings, he is 香蕉视频直播渂locking everything else out and knowing that I got to get in the water, and then more importantly, get out of the water.香蕉视频直播�

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute香蕉视频直播檚 Science and Educational Media Group. The AP is solely responsible for all content.

By Lindsey Tanner

THE ASSOCIATED PRESS