Sleeping naked can improve your sleep quality, support reproductive health, and may offer modest metabolic benefits. Whether it’s definitively “better” depends on your body, your bedroom, and how often you wash your sheets. But the evidence leans in favor of ditching the pajamas for most people.
Why Temperature Matters for Sleep
Your body naturally drops its core temperature as part of falling asleep. Anything that interferes with that cooling process, including heavy pajamas or synthetic sleepwear, can delay sleep onset and reduce the time you spend in deep, restorative stages. Sleep specialists at UCLA Health recommend setting your thermostat between 60 and 65 degrees Fahrenheit for optimal sleep. Sleeping without clothes makes it easier for your body to reach and maintain that lower temperature without fighting fabric insulation.
This doesn’t mean sleeping naked is a magic fix for insomnia. But if you tend to wake up sweaty or kick off your covers in the middle of the night, removing clothing is one of the simplest adjustments you can make. It costs nothing and takes zero effort.
Metabolic Effects of Sleeping Cool
A study conducted at the National Institutes of Health found that sleeping in a 66-degree room for one month increased participants’ stores of brown fat, a type of fat that actively burns calories to generate heat. Unlike regular white fat, which just stores energy, brown fat works more like a furnace. The five men in the study didn’t lose weight from the extra brown fat alone, but they did show metabolic improvements that lowered their risk for diabetes.
Sleeping naked won’t replace exercise or a healthy diet, but it does help your body stay cooler overnight, which is the trigger for brown fat activation. If you’re already sleeping in a cool room, going without pajamas reinforces that effect rather than working against it with an extra insulating layer.
Benefits for Reproductive Health
For men, scrotal temperature directly affects sperm production. Research published in the journal Urology found that clothing raises scrotal surface temperature by 1.2 to 1.5°C compared to the unclothed state. Men with very low sperm counts (under 20 million per milliliter) consistently had higher scrotal temperatures than men with high counts (over 100 million per milliliter). Sleeping without underwear or boxers gives the testes their best chance at staying cool overnight, which is when a significant portion of sperm development occurs.
For women, the logic is about moisture rather than temperature. Synthetic underwear traps heat and moisture against the vulva, creating conditions where yeast can thrive. Going without underwear at night lets the area breathe and prevents moisture buildup. That said, the direct clinical evidence is more nuanced than the advice suggests. A 2019 study found no evidence that underwear style increases the risk of urinary tract infections, bacterial vaginosis, or yeast infections. And a 2005 study found that the vulvar microenvironment, including pH and bacterial balance, didn’t change based on underwear type at all. So while sleeping without underwear is unlikely to hurt and may help if you’re prone to yeast infections, it’s not a guaranteed preventive measure.
The Hygiene Trade-Off
There’s one clear downside to sleeping naked: your sheets take the hit. Throughout the night, your body sheds dead skin cells, produces sweat, and secretes oils. When you wear pajamas, they act as a buffer that absorbs much of this before it reaches your bedding. Without that layer, everything goes directly into your sheets, feeding dust mites and creating a buildup of allergens.
This isn’t a reason to avoid sleeping naked. It just means you need to wash your sheets more often. If you sleep clothed, weekly washing is standard advice. If you sleep naked, you may want to change your sheets every four to five days, especially in warmer months or if you share your bed with a partner or pets. Choosing breathable, natural-fiber sheets (cotton, linen, or bamboo) also helps wick moisture away from your skin rather than trapping it against you.
When Pajamas Might Be the Better Choice
Sleeping naked isn’t ideal for everyone. If your bedroom temperature drops well below 60 degrees and you don’t have adequate blankets, being too cold will disrupt your sleep just as much as being too warm. The goal is a comfortably cool environment, not a cold one.
People with eczema or sensitive skin may also find that direct contact with sheets causes irritation, particularly if the bedding is washed with fragranced detergent or made from rough synthetic material. In those cases, lightweight cotton pajamas can actually protect the skin barrier while still allowing airflow. The same applies if you’re someone who realistically won’t wash sheets more than once a week. A clean pair of pajamas made from natural fibers gives you most of the breathability benefits while keeping your bedding cleaner longer.
The Bottom Line on Sleeping Naked
For most people, sleeping naked is a net positive. It supports your body’s natural temperature regulation, keeps the genital area drier and cooler, and may contribute to small metabolic gains over time. The key requirements are a cool bedroom (60 to 65°F), clean sheets changed frequently, and bedding made from breathable materials. If those conditions are met, losing the pajamas is one of the easiest upgrades you can make to your sleep routine.