Here's Why You Should Sleep Naked, According to Science

I've always slept underwear free. PJ pants, sure — but nothing tighter than that. As a kid, I thought my friends who wore underwear and socks to bed at a sleepovers were absolutely nuts.

Then, at summer camp a few years later, a girl in my cabin took up my cause. When she announced she never wore underwear to sleep, the other kids ridiculed her. No one else believed her when she insisted it was "important to let your vagina breathe at night."

What people wear — or don't wear — to bed is the subject of lively debate. It isn't just about underwear. People have strong opinions about whether it's better to sleep naked or clothed — and if clothed, to what degree. Some folks insist you should wear a bra to sleep, while others balk at the prospect of keeping their boobs caged at night.

Americans seem fairly divided about doffing their clothes in bed. A study by sleep-tech company Airweave found that 52% of Americans opt to sleep "partially clothed." Thirty-one percent sleep "fully clothed," while 17% go "unclothed." For what it's worth, the respondents to my highly unscientific Twitter poll seemed to favor sleeping partially clothed or naked.

What covers America's butts at night?

I got a taste of both sides of this debate when I asked my social media connections how, exactly, they liked to sleep.

Josh Bridge, 23, is adamantly in favor of wearing boxer briefs — and nothing else. It becomes a problem when he's traveling for work and sharing a hotel room. "When forced to wear a shirt for society's sake," Bridge said, "I am very uncomfortable."

Even if it's cold, Melissa Radzimski won't wear anything on the lower half of her body. She argues that it keeps her vagina "pristine." "It is so refreshing because she needs to be aired out!" Radzimski said, echoing my poor, ridiculed summer-camp friend. "And if you're cold, you can wear, like, a hat and/or wear a sweatshirt."

Melissa Radzimski won't wear anything on the lower half of her body. She argues that it keeps her vagina "pristine." "It is so refreshing because she needs to be aired out!"

Meanwhile, Katie Puccio, 22, opts for a crewneck sweatshirt and underwear, no pants. I asked how she didn't sweat to death, sleeping in a sweatshirt every night. "My apartment didn't have heat for a lot of this winter, so I didn't really have another option," she said.

My soon-to-be sister-in-law, Hilary Gray, 23, was straight-up shamed for wearing underwear to sleep — so she never did it again. "When I was younger — first grade, I think — I had a sleepover, and my friend told me it was weird to sleep in underwear," she said. "Ever since then, I haven't." Now, Gray sticks to comfortable pajama bottoms and a big T-shirt. Going underwear-less, she said, is "without a doubt more comfortable."

The people have spoken. So what's actually better for you?

Arguments about comfort aside, I still wanted to find out which option is best for your health. So I called up Shawn Stevenson, author of Sleep Smarter: 21 Essential Strategies to Sleep Your Way to a Better Body, Better Health and Bigger Success.

Health-wise, it's important to let your body cool down during sleep, Stevenson said. Cooling down will lower your blood pressure, which in turn helps your body activate its "rest and digest system" — otherwise known as the parasympathetic nervous system. Cooling down also helps the body release certain hormones and reparative enzymes, he said.

Sleeping naked is obviously more conducive to cooling down than, say, a thick flannel pajama set. But some pajamas are OK, Stevenson said — "we just need to keep it simple, light and loose fitting."

Theresa Fisher, science editor at Casper's sleep news site, Van Winkle's, also spoke of the physical health benefits of sleeping naked. (Fisher is a former contributor at Mic.)

Your body temperature lowers when you're falling asleep and when you're in deep sleep, Fisher told me. "If sleeping naked helps with thermoregulation — if it helps keep your core body temperature low when it's supposed to be low — it would help you fall asleep and sustain deep sleep," she said.

It's important to let your body cool during sleep — so go ahead and strip down.

A 2014 study found that sleeping in colder temperatures helped activate "brown fat," or "good fat," in adults. Brown fat helps burn calories in order to generate heat, and you want "as much of this type of fat as possible," according to Women's Health.

That being said, when it comes to sleep health, you should weigh your physiological and psychological needs, according to Fisher. "If you're not comfortable sleeping naked, the anxiety it produces will probably override the physiological benefits," she said.

Sleeping naked may also have benefits for couples.

Being physically close to other people makes our bodies release oxytocin, a seemingly magical "cuddle hormone" that helps us maintain healthy relationships. Neuroeconomist Paul J. Zak, who goes by "Dr. Love," has famously declared oxytocin is the social glue holding society together.

"If you're sleeping in bed with a partner, skin-to-skin contact could foster the release of oxytocin," Fisher said. "There's at least an argument to be made for both partners sleeping naked, for the sake of their relationship."

Busting two big myths about bras

Sleeping naked, or at least in minimal clothing, seems like the way to go. But sleeping with undergarments proved to be a more complicated issue. Bras, I learned, are a major point of contention.

Bras and cancer: First, there's the idea that women who wear bras 24/7 have a higher risk of developing breast cancer. But according to BreastCancer.org, "There is no evidence to support this claim." It points to a 2014 study that found wearing a bra was "not associated with breast cancer risk," and theorizes how this claim came about.

Can wearing bras at night prevent sagging? Probably not.

Products like the lingerie line Nightlift claim to protect your breasts from "sagging and drooping" while you sleep. But experts say wearing a bra can't prevent sagging; it'll happen naturally, whether you like it or not. "A bra will hold up your breasts to give you the shape and look you want, but it can't prevent further sagging, which is caused by age and gravity," Dan Mills, vice president of the American Society for Aesthetic Plastic Surgery, told Health.

And then there's the matter of underwear.

For people with penises, it could be a good idea to lay off the tight underwear at night. Studies have shown that wearing tight underwear, in general, can affect your sperm count.

How about female-bodied people? It turns out, there may have been merit to my bunkmate's earnest proclamations.

"Though it's a matter of personal preference, from the perspective of breathing and airing things out, you should sleep without underwear," Dr. Donnica Moore told the Huffington Post.

And if you absolutely have to wear underwear, be sure to opt for cotton, which absorbs secretions while still being breathable. "Silk and synthetic fabrics are not breathable," Moore said, "which increases the risk of moisture being trapped and retained, which can create a yeast or bacterial infection."