If you’re someone who has a lot of vaginal discharge or you’re on your period, sleeping in undies “may be your best option to prevent a nighttime mess in the morning,” Ross said.
Those with male genitals, on the other hand, may experience discomfort — particularly in their testicles — if they go commando “due to compression that may occur from their thighs or the mattress while they toss and turn in their sleep,” Spitz said.
If that’s an issue for you, he recommends sleeping in a pair of supportive underwear to prevent any uncomfortable squashing.
Another thing to consider: Wearing underwear to bed means your genitals aren’t making direct contact with your pajamas or your sheets. So you can wash these items a little less frequently — which is a plus if you hate doing laundry.
Sleeping in underwear can also protect the urethra, the tube that connects the bladder to the outside of the body, from irritants or infection, Spitz noted.
For instance, “bed sheets in hotels and friends’ houses may be washed with detergents that may cause irritation to the urethra of some individuals,” he said. “Underwear, even the loose-fitting kind, will serve as a protective barrier to the urethra.”
Spitz also warned that it’s possible for the urethra to get contaminated by bacteria on the bedding where a person’s bare butt has been rubbing against the sheets.
“Since most people don’t change their sheets daily, it’s good to have underwear on, playing defense for the sheets, not only for bacteria, but for leakage of urine or nocturnal emissions of semen that may occur for some,” Spitz added.
Not every pair of underwear in your drawer is well-suited for sleep, though. You’ll want to choose an option that is both comfortable and made of breathable materials.
“Cotton and bamboo are good choices for underwear, as they are soft, absorbent and breathable,” said Dr. Aanand Geria, a dermatologist at Geria Dermatology in Verona, New Jersey.
For sleep, Ross said she recommends full-coverage underwear over thongs because a thong’s “anatomically unfriendly design makes it easier for harmful bacteria of the colon to find their way into the vagina and bladder,” which can increase the risk of infection.
If you’ve ever worried that tight-fitting underwear might affect your fertility, a 2018 Harvard University study found there may be some benefit to wearing loose-fitting boxers instead of briefs that tend to heat up the scrotum. (Researchers looked at men’s general underwear-wearing habits, not specifically their overnight undergarments.) But other research has suggested that choice of underwear makes no appreciable difference on fertility outcomes.
And hopefully this goes without saying, but if you’re sleeping in underwear, make sure it’s a clean pair — not the one you went for a jog in earlier or a pair you pulled from the hamper.
“Since underwear comes in close contact with the skin, it is exposed to sweat, oil, dirt, microorganisms like bacteria or fungus, and even bodily fluids,” dermatologist Dr. Joshua Zeichner, associate professor of dermatology at Mount Sinai Hospital in New York City, told HuffPost. “Sleeping in soiled underwear can contribute to skin irritations or even infections.”
And you may want to sleep commando if…
