Sleep and Cold Water Immersion: Does Ice Bathing Help You Catch More ZZZs?
Michael Haddad, an investment banker based in California, has been sleeping better since he began ice bathing, also known as cold water immersion (CWI), 24 months ago. "I'd sometimes have trouble falling asleep and staying asleep," he said. "Since I've been using the BlueCube Baths Hydro Healer, my sleep has improved dramatically. I fall asleep faster and don't wake up as often."
Haddad is not alone. Many people, from amateur and professional athletes to CEOs, weekend warriors and amateur yogis, have raved about how CWI has improved their sleep. The popular podcaster and lifehack blogger Tim Ferriss, who wrote the bestselling book The 4-Hour Workweek and has focused much of his content on deconstructing world-class performers, compared the impact of ice-bathing an hour before bedtime to “getting hit with an elephant tranquilizer.”
Dr. David Geier, a double-board certified orthopedic surgeon and sports medicine specialist, also touts the benefits for sleep and said it has helped him sleep better as well. Visit YouTube and search for “cold water immersion” or ice bathing, and you’ll find plenty of instructional videos and testimonials, raving about CWI’s benefits for sleep.
A highly skeptical New York Times writer was converted after doing a yoga/meditation/ice bath class, noting she “felt joyous and tired” afterward: “I walked across the street and bought lobster breakfast tacos as a kind of celebration. I had made it to three minutes of ice bathing and even opted to stay an extra 30 seconds. I did it purely for the sake of challenging myself, and I was eager to do it again.”
Sleeplessness – in the form of insomnia and any of a number of other sleep disorders – is a huge problem. It’s estimated to cost the U.S. economy 1.2 million working days a year in productivity. And it’s one of the biggest threats to individual health out there. It’s been well documented that losing sleep can increase your risk of accidents, predispose you to diseases, negatively affect your memory, mood and cognitive functioning, lower your sex drive and lead to weight gain.
Increasing awareness of those facts may have helped fuel the current interest in ice bathing and CWI. But cold water baths have long been popular for a variety of therapeutic purposes, dating back to 3500 B.C. CWI was used in various forms to treat fevers and a variety of other ailments, and for spiritual or meditative purposes.
But what does scientific research say about its benefits for sleep, which has long been said to be the best recovery regimen out there, for both sports demi-gods and the rest of us mere mortals?
A review of available research studies and scientific literature shows better sleep through cold water is, well, a thing! The exact physiological mechanisms – brain chemistry? hormones? stress response? – are not well understood, and many of the studies were focused primarily on athletic recovery from training and subsequent performance, with positive impacts on sleep noted as an ancillary benefit.
- Turn the body thermostat down. It is well established that core temperature in people and other mammals drops before and during sleep. This process is known as thermoregulation, and it’s controlled by circadian rhythms that start to drop the body’s core temperature – a total of about 1.8 degrees – as we prepare for bed. That temperature drop is a critical component of a good night’s sleep. Ice baths (obviously) lower core body temperatures. Other studies have correlated that lower core temperature with increased production of melatonin, the natural sleep hormone that helps prepare us for rest.
- Fall asleep harder and faster. In a study in the journal Frontiers in Sports and Active Living, researchers found that male endurance runners who engaged in partial or whole (head included) cold water immersion after intense training had a “significant” decrease in limb movement. They also had a significant decrease in arousal, which is an abrupt change in the pattern of brain wave activity. That’s when you’re jolted from deep sleep to light sleep, or light sleep to wakefulness. It also found that slow-wave sleep – deep sleep – was increased in the early part of the sleep cycle.
- Build on better sleep over time. A study of male swimmers found that those who used CWI immediately after their training sessions reported better and better sleep over the course of several days during the study.
It’s in your head - literally. Dr. Daniel Buysse, a psychiatrist at the University of Pittsburgh School of Medicine, has shown through his studies that people with insomnia tend to have more activity in their brain’s frontal lobes (your brain’s project manager – where planning, organizing and logical reasoning takes place). He found that, basically, the extra brain activity was keeping the brain physiologically too hot to sleep. Using specialized cooling caps, study subjects achieved better sleep, nearly as good as the control group, who did not have sleep disorders.
You need good sleep. And with mounting evidence that CWI may help you catch more and better sleep, try BlueCube Baths’ Hydro Healer.
1 - Harding EC, Franks NP, Wisden W. Sleep and thermoregulation. Curr Opin Physiol. 2020 Jun;15:7-13. doi: 10.1016/j.cophys.2019.11.008. PMID: 32617439; PMCID: PMC7323637.
2 - Dijk D.J., Czeisler C.A. Contribution of the circadian pacemaker and the sleep homeostat to sleep propensity, sleep structure, electroencephalographic slow waves, and sleep spindle activity in humans. J Neurosci. 1995;15:3526–3538.
3- Chauvineau M, Pasquier F, Guyot V, Aloulou A, Nedelec M. Effect of the Depth of Cold Water Immersion on Sleep Architecture and Recovery Among Well-Trained Male Endurance Runners. Front Sports Act Living. 2021;3:659990. Published 2021 Mar 31. doi:10.3389/fspor.2021.659990
4 - Al Haddad, H., Parouty, J., & Buchheit, M. (2012). Effect of daily cold water immersion on heart rate variability and subjective ratings of well-being in highly trained swimmers. International journal of sports physiology and performance, 7(1), 33-38.