Why do you sweat the bed?

No, changing your pajamas in the middle of the night is not normal.

Bed sweating is not a topic for dinner party conversation, but it's an issue for many people that can, in some instances, be refreshingly simple to addressed if acknowledged. Body temperature naturally drops during sleep; however, many people perspire at night, and sometimes excessively. It could be due to a lot of things, but the culprit is often simply an overheated bedroom or sleeping with too many bedcovers, says Deena Adimoolam, M.D., an assistant professor of endocrinology, diabetes and bone disease at the Icahn School of Medicine at Mount Sinai in New York.

For starters, make sure your bedroom temperature is set to an optimal 68 degrees. Consider swapping synthetic bedding for sheets made from natural materials, like cotton and wool, which have better absorption and aeration. And evaluate your mattress, too. Older memory foam mattress can absorb and radiate body heat, so consider a brand that uses all-natural materials (Hästens, for example, has a layer of horsehair that uses capillary action to absorb body moisture, says Perla Munhoz Bovin, the company's research and development manager).

But if you’ve kicked off the sheets, gotten a new bed set, have icicles forming on your bed frame and still wake up in a personal sauna, it's time to call in the experts. Here are some possible sleep sweat culprits:

Sleeping in the nude

Counterintuitive, yes, but people who sleep naked may be more likely to sweat, says Raymond Gottschalk, M.D., an internist and sleep disorder specialist at The Sleep Disorders Clinic in Hamilton, Ontario. “Wear something to bed, such as a cotton t-shirt,” he advises. “It’s absorbent and allows you not to have so much bedding on top of you,” which helps prevent overheating.

Working out too late

After a sweat session, it can take sometimes two to four hours for your body temperature to return to normal, explains Gottschalk. If you go to bed in that window of time, it could be the reason for your sweaty sleep. The best time to exercise (vis-à-vis sweating the bed) is five or six hours before bedtime, he says, because those extra hours mean you’re going to sleep on the cooling curve of your body’s core temperature.

Note that regular exercise improves sleep as long as you leave a sufficient buffer between your workout and your bedtime. “We believe exercise raises core body temperature and strengthens the hypothalamus’s ability to drop core body temperature at bedtime, which signals the onset of sleep,” says Robert S. Rosenberg, M.D., a board-certified sleep medicine physician and author of Sleep Solutions for Stress & Anxiety. “Exercise also appears to increase deep, slow-wave sleep.”

Eating too late and/or spicy foods

If your evening meal is on fire, you could be in for a long night. Foods that can trigger GERD or heartburn can also bring on sweaty sleep, as can eating too late in the evening. Much like you don’t want your body to be busy snoring while you’re sleeping, you don’t want your digestive system working overtime either, as that’s another common cause of night sweats. “You want to eat fairly early in the evening to avoid taking too much digestive activity with you to bed,” Gottschalk says. “More than 70 to 80 percent of your heat is generated from your internal organs, so if there’s activity stirring the pot inside you, there’s going to be more heat generation.”

Hormonal conditions

Because the hormone fluctuations of periomenopause and menopause can trigger the body’s sympathetic nervous system—or the “fight or flight” response—they affect its ability to regulate temperature. Therefore, periomenopause and menopause are common culprits of excessive sweating at night for women. (Disorders such as hyperthyroidism could be causes as well.) Talk to your doctor and test the upper limits of your air conditioner.