You’ll sleep better
Shedding your threads before tucking in will help you snooze more soundly, says Men’s Health sleep advisor W. Christopher Winter, M.D. Your body temperature declines as you doze and climbs before you wake up, but clothing can interfere with this natural fluctuation, Dr. Winter says. The extra insulation can make you too hot as your temperature drops, leading to tossing and turning and waking up sweaty in the middle of the night. Nix the PJs and allow your body temperature to ebb and flow uninterrupted, Dr. Winter says.
You’ll ignite your metabolism
Staying cool throughout the night may help rev your metabolism, according to a 2014 study in the journal Diabetes. Researchers found that when people slept in a chilly room, they produced double the volume of brown fat—a healthy fat stored in your neck that burns calories to generate body heat—compared to when they slept in a warmer room. Keeping your body temperature lower by sleeping unclad could produce the same effect, says study author Francesco S. Celi, M.D.
You’ll protect your testicles
Sleeping in your underwear increases the odds that you’ll get an infection in the worst possible place, says Brian Steixner, M.D., a urologist based in Atlantic City, N.J. Your underwear keeps heat and moisture in—and bacteria thrive in warm, moist environments, says Dr. Steixner. More bacteria makes for a higher likelihood that any chaffed or irritated skin down there becomes infected, he says. Skip your skivvies to keep “southside” cleaner, drier, and healthier.
You’ll nurture your sperm(men)
Your scrotum needs to be just the right temperature in order to optimize sperm production, says Dr. Steixner. That perfect temperature: 95 to 96 degrees, just slightly cooler than the rest of your body. When your testicles are too warm, your sperm quality suffers, according to a Finnish study that tested the semen of men who used saunas. Even tight underwear can be enough to raise your sack’s temperature above the optimum level, Dr. Steixner says. So for the sake of your future children, consider freeballing.
You’ll get closer to your partner
Skin-on-skin contact with another person triggers the release of the hormone oxytocin in your brain, according to Swedish researchers. The chemical reduces stress, makes you feel more connected to your partner, and increases your s*x drive, the scientists say. And let’s state the obvious: Brushing up against each other unclad in bed often leads to good things.