Q. Do cold plunges really offer health benefits?
A. Records describing health-related cold plunges date back to the fifth century b.c., when ancient Egyptians, Romans, and Greeks purified themselves in chilled baths to promote general well-being. Scandinavians have taken post-sauna dips in icy water for more than 1,000 years.
Modern experts are split on whether the old-timers were on to something. Cold plunges, now used by everyone from football players to Olympic athletes, are certainly rejuvenating, since they stimulate the release of norepinephrine (a stress hormone and neurotransmitter) and epinephrine (a.k.a. adrenaline), both of which feel invigorating when they course through the body. According to Anne Bramham, who founded the American Spa Therapy Education and Certification Council, going from hot to cold is a great cardiac workout that elevates the pulse rate and increases circulation. "It's an excellent tonic for the nervous and circulatory systems and helps tone the skin," she adds.
Only problem: there's no scientific evidence for those assertions. Physiologists generally agree that any health benefit of cold plunges is imagined—a by-product of that sense of well-being. "They make you feel alert and refreshed," says Mike Tipton, professor of human and applied physiology at England's University of Portsmouth. "But there is no conclusive evidence of improved immunity or other health benefits." Tipton also points out that cold plunges are "potentially dangerous" for people with cardiac and blood-pressure issues, since they stress the cardiovascular system. But if you're healthy and they make you feel good? Hop in.