You wouldn't believe the questions I get when people find out that I study sleep for a living. There is one sleep related question in particular that has popped up numerous times over the past six months - "Is it better to sleep naked?". Some people ask because they want affirmation that their sleeping habits are socially (and biologically) acceptable while others have heard anecdotal evidence that it helps performance . While I don't have any answers regarding the social implications for ditching your pajamas, I can address the biological argument for sleeping naked. Yes, it is true. Sleeping naked is better, especially for an athlete in training.
It's All about body temperature
The most convincing argument for sleeping naked is that it keeps your core body temperature as close as possible to its set point at a time when you are very vulnerable to the outside world (ie, sleeping). To provide some background, our core body temperature fluctuates across a twenty-four hour period. There are two peaks and two dips in our core body temperature (CBT for short) that are controlled by areas deep in the brain. When we wake in the morning, our CBT rises. Around lunchtime, our CBT peaks and begins to fall thereafter. In the early afternoon, our CBT reaches a low explaining why we are sleepy and need a nap or coffee.
Side Note: For athletes, it is better to opt for a nap over coffee. I spend a lot of time in my recent book Meathead: Unraveling the Athletic Brain discussing the numerous benefits of a twenty-minute nap for improving mental and physical performance.
In the late afternoon, whether or not you've taken a siesta, CBT begins to rise and peaks a second time in the late evening. This is the biological explanation for why people get a "second wind" around 10 PM. Thereafter, our body prepares itself for a good night's rest and CBT declines reaching another low in the middle of the night around 3-4 AM. Of course, not everyone has the exact same fluctuation in CBT, but this is the general pattern.
Ditch the pajamas
So how does not sleeping naked affect CBT? The answer is pretty simple. Wearing those comfy flannel pajamas and nightgowns tends to elevate your CBT even if you don't sleep under the covers. PJs hug your body and provide insulation. This prevents the full range of natural peaks and dips in CBT and negatively affects sleep quality as a result. Over the past three decades, scientists have identified a very intimate relationship between sleepiness, sleep quality, and CBT. When our CBT drops, the body prepares itself for restorative sleep. When our CBT rises, the body prepares itself for being awake.
As I've also discussed in Meathead: Unraveling the Athletic Brain, having quality, uninterrupted sleep helps our body repair, recover, and prepare itself for the battles it faces the next day. We release two very important hormones during sleep that are released in very low quantities while awake: growth hormone and insulin growth factor. Of course, growth hormone is the more recognizable hormone to athletes, but both of these hormones--growth hormone and insulin growth factor--help to build muscle, bone, and reduce inflammation.
less is more
The bottom line is this - Sleeping naked will help ensure that your body's temperature doesn't artificially rise at night. The closer you can keep your body temperature to it's natural state, the higher quality and more rejuvenating your sleep will be. As a side benefit, you might even find that it helps to increase the love and emotional attachment between you and your partner. And by your partner, I don't mean CrossFit!
About Allison Brager:
Professional: Academic Researcher with a focus on neurobiology @ Morehouse School of Medicine and professor at Morehouse College
PHD Info: Kent State with a focus on neurobiology (PHD from Department of Biological Sciences)
CrossFit Games Experience: 2014 Regionals Athlete, 2013 CrossFit Games - Team, 2012 Regionals Athlete
Collegiate Athletic Background: Brown University Track & Field, 4 year varsity letterman, specialist in pole vault and hurdles
Facebook: Meathead: Unraveling The Athletic Brain
Allison's Blog: www.dormivigilia.com
Instagram and Twitter: @beastlyvaulter
Special thanks to Lauren Brooks for giving us permission to use her pictures in this article. She finished 7th at the 2014 CrossFit Games and is one of the fittest women on the planet. For those of you who don't know about her, crawl out from under your rock and check out her instagram account @cflbrooks.
We would also like to thank Allison for submitting another phenomenal piece. She's a true modern day Renaissance Woman who somehow manages to juggle her scientific pursuits, athletic career and writing. If you would like to know more about Allison, check out our recent interview with her here and her competition tips here.
Let us know if sleeping in the nude helps improve your performance - we might just choose you as our Athlete Of The Week!