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Why Do Some People Sweat When They Fall Asleep?

Turns out, even night sweats are gendered

Night sweaters can be divided into three categories: Men, women and children. “The reasons why people sweat at night is quite gendered,” says Rafael Reisfeld, a surgeon at the Center For Hyperhidrosis.

But hold up: First, what the hell are night sweats anyway?

According to the Mayo Clinic, night sweats — also known as sleep hyperhidrosis — are repeated episodes of extreme perspiration, intense enough to soak through your pajamas or sheets. Now, if you woke up in a puddle of your own sweat a couple times last month but it hasn’t happened since, you can probably just blame that on the weather. But: “If you’re sweating at night more regularly, it’s categorized as night sweats and that could be because of some underlying disease or malignancy, like tuberculosis or some other infectious disease,” says Reisfeld.

Weight can also be a cause. “The number of sweat glands you have depends on your body’s surface area,” says Reisfeld. “So if you’re heavy, you have more sweat glands per inch.”

But while those potential causes of night sweats apply to both men and women, Reisfeld tells me there’s another reason, which is mostly reserved for women. “Women are more likely to experience night sweats because they experience more hormonal changes in their body,” says Reisfeld. “Men also experience hormonal changes, but not nearly as extreme as women.”

According to Body Logic MD, night sweats for women is one of the most recognizable symptoms of menopause and hormone imbalance: “Much like hot flashes, low estrogen and its effect on the hypothalamus [the part of the brain that controls appetite, body temperature, sleep and sex hormones] is often specifically what causes night sweats in women. Reduced natural estrogen levels fool the hypothalamus into believing that the body is too hot. Subsequently, a night sweat occurs in an effort to purge the body of this fictional excess heat.”

Which is why Reisfeld suggests that women should see their gynecologist or an endocrinologist if they experience damp pajamas on a regular basis. “They’ll likely be put on HRT [hormone replacement therapy],” he advises.

That also brings us to kids. They’re young, they’re (hopefully) healthy and they’re likely not experiencing any menopausal symptoms. So why, when you go to kiss your sleeping little one on the forehead on your way to bed, is it sometimes drenched in sweat?

The answer is disarmingly simple: Dreams. “They put you in an excited state and increase your anxiety levels,” says Reisfeld. While he’s unsure whether such sweating is caused by bad dreams or good ones, according to, nightmares are certainly capable of activating your body’s stress response, which can include profuse sweating. Reisfeld adds that sweating resulting from dreams isn’t exclusive to children, either. “Adults can experience it too,” he says.

So next time you randomly wake up in a puddle of your own sweat, chances are it’s because of some work-related stress dream. Or y’know, another kind altogether.