(Not yet) a common cure
Enter into the conversation Mark Harper, MD, PhD, consultant anesthetist at Sussex University Hospitals in the United Kingdom and Kristiansand, Norway. Dr. Harper is the author of the 2022 book, Chill: The Cold Water Swim Cure – A Transformative Guide to Renew Your Body and Mind.
Dr. Harper grew up swimming in pools, and it wasn’t until his pool closed for 2 weeks that he ventured into the sea. He recalled walking up the beach afterward, thinking, God, this feels good, and from that moment on, he became hooked on outdoor swimming and curious about its therapeutic potential.
The “cure” in the book’s title, Dr. Harper explained, is being used in the historical sense of “treatment,” as in the first medical book about sea-bathing written over 250 years ago. Dr. Harper acknowledged that the connection to health is still speculative. “However, the circumstantial evidence, the feedback from participants and early study data for its benefits are now very strong,” he said.
In a small study published in 2022, Dr. Harper and colleagues took 59 people with anxiety and depression and put them through a sea-swimming course. Afterward, 80% showed a clinically significant improvement in their mental health.
More recently, Dr. Harper and his team of researchers released a survey to determine how many people were using cold-water swimming as a treatment for a mental or physical ailment. “We thought 30 or 40 people would respond, but we ended up with over 700,” he said. “The majority were using it for mental health but also included inflammation-related conditions.”
Over 2 decades, Dr. Harper has seen dramatic success stories. In his book, he recalled a good friend who, in his early 20s, suffered from Crohn’s disease so badly he couldn’t walk up the steps to his parents’ house. The friend turned to outdoor cold swimming as a low-impact workout and began noticing the symptoms of his disease were improving. Within months, he was able to go off his medications. In 2022, he completed 52 triathlons: one per week for the entire year.
How cold exposure may play with your brain
Vaibhav Diwadkar, PhD, professor of psychiatry and behavioral neurosciences at Wayne State University, in Detroit, is studying how human brain networks respond to cold exposure. Dr. Diwadkar and his colleague, Otto Muzik, PhD, began by putting volunteers in a rubber suit with thin tubing and infusing the tubing with temperature-controlled water. Meanwhile, they collected functional brain imaging data to analyze which parts of the brain were responding as body temperature changed.
The data showed that the cold exposure made certain areas of the brain very active, including some that have been associated with the regulation of mood.
Dr. Diwadkar posits that controlled exposure to cold serves as a low-level stressor that knocks different systems within the brain and body out of homeostasis. Once the stress is removed, the brain responds by releasing neurotransmitters that enhance mood, frequently leading to feelings of euphoria in participants.
“We don’t have direct evidence of such a mechanism, but it’s a reasonable speculation,” said Dr. Diwadkar.
However, he pointed out that science writers in the media often portray topics such as this one in black and white, which is “oversimplifying the scientific complexity of biology.”
Clearly, more research needs to be done on the potential therapeutic benefits of cold-water swimming. But for those suffering from anxiety, depression, or chronic illness, if taking a cold dip makes you feel better, the why and how might be beside the point.
Plus, as Dr. Harper pointed out, it’s an easy and accessible therapy.
“All you need is some water – enough to submerge your entire body in – that’s less than 68 °F (20 °C),” he said. “If you stay long enough to get over that initial shock, which is just 2 or 3 minutes, then you’ve got the effect. If you get out and want to go back in again, then you’ve done it right.”
A version of this article first appeared on Medscape.com.