Why You Sweat So Much at Night—And What to Do About It

Waking up in a pool of sweat can feel alarming. And even though lots of people sweat more overnight, it’s a sign that things may not be working as they should: the body’s core temperature typically decreases slightly during sleep.

But a variety of medical and lifestyle factors can signal to the brain that it’s time to start sweating, leading to scorching-hot wakeups. We asked experts how to figure out what’s leading to those sweat-drenched sheets, and what to do about it.

It could be a medical issue

Sweating at night can indicate that something is going on health-wise, says Dr. Aarthi Ram, a sleep medicine specialist at Houston Methodist. You could be going through menopause or have an abnormal thyroid or a neurological disorder—or even an infection like tuberculosis, malaria, or typhoid fever. “That's why it’s important to go over travel history with your doctor,” she says. In some cases, night sweats can manifest in people with cancer, but that’s just one of numerous possibilities, she says.

Another possibility is obstructive sleep apnea. Findings from an Icelandic study of people with sleep apnea have found that people with the condition experience night sweats at a rate three times higher than the general population. “Anecdotally, I’ve had a few patients who have seen their ob-gyn and primary care provider, and they come to see me and they're like, ‘No one can figure out why I have these night sweats,’” Ram says. “We do a sleep study, and they end up having sleep apnea.” Treatment, she adds—like wearing a CPAP mask—greatly improves their nighttime sweats.

So when is it time to see a doctor? “If you're waking up drenched in sweat nightly, and it's causing a significant disruption in your sleep or functional impairment, that's usually a good indication,” Ram says. Expect your doctor to take a detailed history and run some basic labs.

Your medication might be to blame

Lots of common prescriptions can cause people to heat up at night, says Dr. Shoshana Ungerleider, an internal medicine physician who hosts the TED Health podcast. Among them: antidepressants, hormone therapy, diabetes medications, steroids, and beta blockers. “If you’re concerned a new medication is leading to your sweating at night, think about asking your doctor about timing or if the dosage could be changed,” she suggests. Sometimes, small adjustments can lead to better sleep.

Read More: How to Sleep When It’s Really Hot Outside

You may be eating and drinking the wrong things

If you enjoy a nice little bedtime snack that happens to be, say, in the jalapeño family, reconsider. Consuming spicy foods before going to sleep can trigger sweating. Alcohol and caffeine are also common culprits. “You definitely want to avoid alcohol before bedtime,” Ram says. “It can change your sleep architecture and cause night sweats.” It’s best to cut yourself off a few hours before bedtime.

Or you’re stressed

Stress and anxiety can trigger the fight-or-flight response—a surge in sympathetic nervous system activity—even when you’re asleep. “You can absolutely wake up drenched in sweat because you’re worried about things,” Ram says.

That’s why it’s worth trying to relax for an hour or so before going to bed. Dr. Glynis Ablon, a dermatologist and founder of the Ablon Skin Institute & Research Center in Manhattan Beach, Calif., advises her patients to adopt habits like meditating or taking a bath with Epsom salts, which she enjoys every evening. “Make your environment as relaxing and non-stress as possible,” she says. That might include putting your phone in another room, hanging up blackout curtains to block annoying light, and playing calming sounds on a white noise machine.

Your bedding could be heating you up

Bedding choices play a big role in sweaty sleep.

The most breathable fibers are the natural ones, notes Parima Ijaz, a textile expert and founder of the bedding brand Pure Parima: “Cotton, linen, hemp, and bamboo all allow air to pass through easily, helping cool the skin,” she says. Each one, however, has pros and cons; linen and hemp, for example, are prone to wrinkling and have a coarse texture that not everyone will like. Experiment to figure out what you find most comfortable. And if possible, go with a Percale weave. That’s a construction style that “allows for more air to pass through,” Ijaz says. It also has a lighter weight and crisper feel than other styles.

Read More: How to Deal With Sweaty Feet

If you want to layer up, look for a blanket or comforter that’s lightweight, breathable, and made out of natural fabrics, like a down alternative comforter made out of cotton. (Down is an insulating fiber that traps heat, which is why alternative fills are best for hot sleepers, Ijaz says.) Avoid wool and fleece, which are too good at keeping you warm. The same goes for synthetic materials like polyester, microfiber, and acrylic.

If new bedding isn’t in your budget, get creative, advises Terry Cralle, a registered nurse and clinical sleep educator near Washington, D.C. You could put your top sheet in the fridge or even the freezer for about half an hour before you go to bed. How’s that for a cool pathway to less sweating? “I thought it was so clever,” she recalls of the first time someone told her about the trick—and it works.

It might be time to replace your mattress

When people consider potential mattresses, their attention often centers on whether it’s soft or firm. But breathability matters, too, Ram says—it determines how much airflow will circulate. “Sometimes memory foam mattresses tend to be a little more dense, and they can trap heat,” she adds. “Innerspring mattresses promote more airflow because of the empty space between the coils.”

Some mattresses and mattress toppers are infused with cooling material—like temperature-regulating gel beads and moisture-wicking fabric covers—and can elevate the sleeping experience. You could also consider technology like the BedJet, which blows cool air under the sheets, or a Chilipad system, which can ensure your bed stays as low as 60°F. “When I see people come in who are miserable and hot, they often haven’t looked at these new products in years,” Cralle says. “There are so many solutions and options for people out there, and it comes back to, do you value your sleep?”

Or you need new pajamas

If you’re a hot sleeper, avoid wearing anything made out of synthetic fabrics—including, perhaps counterintuitively, satin nightwear. That’s because the fabric, while pleasant to touch, isn’t breathable, Ijaz says. Polyester and nylon tend to trap heat, too. Instead, opt for pajamas made out of natural fabrics such as cotton, linen, and hemp, she suggests. Sweaty people might also find that sleeping in the buff is the coolest option.

Your thermostat might be set too high

The ideal temperature for sleeping typically ranges from 60 to 67°F, Cralle says. If you need help getting there, turn on the AC or enlist some fans—she knows people who set up a few around their bedroom. Fans work well for air circulation and “help evaporate moisture without necessarily waking you up,” she says. Another idea: Put a bowl of ice in front of the fan right before you go to bed, and enjoy an extra-cool breeze, Cralle suggests. It’s just one more way to ensure you don’t lose sleep over yet another sweaty night.