OK, TMI: Why Do I Sweat in My Sleep?

“Don’t sweat it” is a pretty common turn of phrase in U.S. vernacular, typically meant to tell people not to worry or stress about something. But what do you say if the whole reason why you’re stressed is because, well, you can’t stop literally sweating in your sleep?

Night sweats, the clinical term for when you sweat through your clothes or sheets while you sleep, can be uncomfortable at best and disruptive to your sleep at worst. It’s a fairly common issue, too: Research shows that up to 41 percent of primary care patients report experiencing night sweats. (It’s most common among adults in their 40s to mid-50s.) Suffice to say, if you’ve ever found yourself frantically asking Dr. Google what the heck is going on, you’re not alone.

We chatted with a few leading sleep experts to uncover the most common night sweat causes. Keep reading to learn how to stop night sweats once and for all—as well as when to be concerned about night sweats if they persist.

What are night sweats?

Night sweats are exactly what they sound like: excessive sweating at night while you’re asleep. The primary symptom is sweating at night that is so severe that your sheets and/or pajamas get damp or even soaked.

Abhinav Singh, MD, FAASM, medical director at the Indiana Sleep Center and a medical review expert at SleepFoundation.org, says that night sweats are typically not a cause for concern. In many cases, they often are an indicator to tailor your lifestyle and sleep hygiene choices. (Think: Is your room too hot at night, or are you wearing too many layers to bed?)

“Sweating is the body’s response to overheating so that the body may cool itself,” —Nilong Vyas, MD

However, you should be more concerned if night sweats happen often, since that can be a sign of a more serious underlying problem (more on that in a minute). Dr. Singh adds that ongoing night sweats can cause you to wake up abruptly, which can set off an insomnia cascade. “And as we age, middle-of-the-night awakenings can be harder for returning to sleep,” he says. “Repeated occurrences can make insomnia more common with daytime impact.”

What causes night sweats?

Night sweats are caused by an unregulated internal body temperature—aka getting too hot while asleep. “Sweating is the body’s response to overheating so that the body may cool itself,” says sleep expert Nilong Vyas, MD, founder of Sleepless in NOLA and a medical review expert at SleepFoundation.org.

While the obvious cause of night sweats is getting overheated, that feeling is actually merely a symptom of other causes. These things can be external triggers (like room temperature and alcohol consumption) or internal (such as certain illnesses or health conditions that impact your ability to regulate your temperature).

External factors that can cause night sweats

Your environment and/or lifestyle choices can trigger night sweats. Be mindful of the below when looking to enjoy a dry night’s sleep.

1. Room temperature

According to Michael Breus, PhD (aka The Sleep Doctor), the temperature of your room or surroundings greatly affects the body’s ability to regulate its own temperature. If the room is too hot, it’s natural for your body to start sweating to cool down. (The ideal room temperature for sleeping varies from person to person, but tends to be in the 60-67 degree Fahrenheit range.)

“In fact, your body needs to lower to a particular temperature in order for it to produce [the hormone] melatonin—which is kind of the key that starts the engine for sleep,” Dr. Breus adds. “So when you are hot, no melatonin, and no sleep.”

2. Heavy bedding or sleepwear

You may love snuggling up with thick quilts, ultra-fluffy comforters, and fluffy socks and sweats in fall and winter, but during spring and summer, they can be way too warm. Enter: night sweats.

3. Bed-sharing

Dr. Vyas says that bed sharing can often make people overheat. Think about it: If your body has trouble regulating its own temperature, imagine what happens when you get in bed with people and pets that are up against the same fight.

4. Alcohol consumption too close to bed

There’s a good reason why sleep experts pretty universally recommend that people consume less alcohol: it is a notorious sleep disruptor. “While alcohol is initially sedating, once it is metabolized it can lead to disrupted, poor quality of sleep later in the night,” neuroscientist Kristen Willeumier, PhD, previously told Well+Good.

Alcohol can also trigger night sweats, Dr. Vyas says. The mechanism is a little complicated. But according to American Addiction Centers, alcohol acts as a vasodilator, meaning it widens your vessels. Wider blood vessels let blood travel faster throughout your body, distributing heat and making you flushed. Your liver also creates heat as it works to process the alcohol. This might make you feel warm and trigger sweating.

5. Medications

Certain medications can have night sweats as a side effect because they can impact your body’s ability to regulate temperature. Dr. Singh says that antidepressants, hormone therapies, and steroids are the general drug categories most likely to cause night sweats.

There are various reasons why a medication could cause night sweats. For example, selective serotonin reuptake inhibitors (SSRIs), a common type of antidepressant medication, may block a certain kind of receptor in your brain that impacts your heart rate and body temperature, which could trigger excessive sweating. (In fact, an estimated 20 percent of patients on antidepressants deal with excessive sweating.)

Internal factors that cause night sweats

Internal factors that cause night sweats are those intertwined with your physiology, or the normal functions of your body. When these functions are disrupted (say through hormonal changes, infection, or disease), night sweats can occur.

1. Perimenopause and menopause

Hormonal changes are the cornerstone of perimenopause, when your ovaries gradually stop making the sex hormone estrogen. When these hormone levels decline, hot flashes and night sweats become much more common, Dr. Singh says. The specific underlying mechanism as to why a lack of estrogen can trigger hot flashes is not fully understood yet. But experts believe that the changes in estrogen make it harder for your hypothalamus (the part of your brain that controls stuff like body temperature and heart rate) overreact to changes in body temperature. This can trigger hot flashes and sweats (including night sweats) as your body struggles to keep its equilibrium.

2. Infection

According to Dr. Singh, night sweats may be a clear indication of your body’s attempt to fight off an infection. Infections can lead to fevers, which can obviously lend to feeling particularly hot (or developing cold sweats) at night. Common colds and the flu are known to trigger fevers, chills, and cold sweats. Your night sweats might coincide with other symptoms like fever, muscle aches, and swollen lymph nodes. “Infections such as tuberculosis, HIV, and endocarditis [when bacteria makes its way through the bloodstream into the heart valve] are associated with night sweats,” he adds.

3. Hyperhidrosis

Dr. Breus says hyperhidrosis is another potential cause of night sweats. Hyperhidrosis is the clinical term for excessive (ie: dripping) sweating, and is caused by certain illnesses, medications, or having an underlying genetic condition. In most instances, hyperhidrosis shows up on the hands, feet, face, and under the arms. This condition is diagnosed through lab and/or sweat tests to determine the severity and to identify if there are any other underlying causes for your excessive sweating.

4. Stress and anxiety

Dr. Singh says that for some people, chronic stress and anxiety can manifest into night sweats. People with post traumatic stress disorder (PTSD) also often experience night sweats and other sleep disturbances. This makes sense considering both stress and anxiety can cause nervousness, which can lead to sweating in waking activities, too. In fact, researchers found that people with hyperhidrosis have anxiety and depression at higher rates compared to the general population.

5. Sleep apnea

Sleep apnea—a serious sleep disorder where breathing stops and starts while you’re asleep— and night sweats can go hand in hand, Dr. Singh says. This happens because when a person with sleep apnea stops breathing, their blood oxygen levels drop, which then triggers the body to sweat.

6. Thyroid problems

According to both Drs. Breus and Singh, an overactive thyroid—the gland that releases hormones to regulate your metabolism and more—can also be to blame for night sweats. Hyperthyroidism (where the thyroid gland produces too much thyroid hormone) can make people very sensitive to heat and is associated with night sweats and excessive sweating in general.

How to deal with night sweats

Since there are so many potential causes of night sweats, it helps to narrow down why you might be experiencing the nocturnal sleep disturbance.

First, try to rule out any lifestyle factors that might be triggering night sweats. Obvious low-hanging fruit includes making sure your room is cool enough for sleeping. “Keep the room at a stable temperature between 65 and 75 degrees Fahrenheit,” Dr. Breus says, suggesting the lower end of the spectrum for the most comfortable sleep. (Adults over 65 years old might benefit from higher temps between 70 and 74 degrees Fahrenheit, according to new research.) If you have less control over the indoor temperature in your bedroom, try adding a fan for air circulation and movement instead.

Consider ditching heavy bedding and sleepwear in order to stay cool, too. Look for moisture-wicking material like bamboo, lyocell, and cotton in both your bedding and PJs. (Or if you’re feeling it, sleep nude!)

As for alcohol consumption: Dr. Breus says you should stop drinking four hours before bed to prevent night sweats. And evaluate how much you’re drinking, too, since women who consume eight or more drinks per week may be more prone to excessive drinking-related health conditions (including stuff like night sweats). If you’re open to a sober curious lifestyle, consider opting for a mocktail before bed instead.

Managing stress and anxiety might also help reduce your risk of night sweats. The specifics depend on what work best for you, but some options may include: changing your bedtime routine to include a relaxing bath or shower infused with essential oils for anxiety; taking a sleep-boosting magnesium supplement or eating foods high in magnesium and other sleep-promoting nutrients; regularly meditating using the Headspace or Calm apps (or other tool of your choice; doing yoga regularly; getting support from a loved one or mental health professional.

If you’re taking antidepressants, oral steroids, or other medications that might be linked to night sweats, talk to your doctor about how to mitigate the side effects—or whether it’s worth trying a different medication. Do not stop taking it without consulting your health-care provider.

When to see a doctor about your night sweats

There are a few tell-tale signs that it’s time to see a doctor for your night sweats: if you’re losing sleep and/or soaking your sheets and clothes on a regular basis, if tackling lifestyle factors like bedroom temperature isn’t helping, and if you know you have an underlying condition that might trigger night sweats, like perimenopause. All of these situations mean that you need a health-care provider’s help and support to understand the underlying cause of your night sweats, as well as more targeted, clinical care.

What night sweat treatment entails depends on your unique health situation. For example, if hormonal changes due to perimenopause are the culprit, your doctor might recommend hormone therapy, which replaces the dwindling estrogen in your body to mitigate some of the worst side effects. (Hormone therapy has been shown to be safe and effective for perimenopausal women under the age of 60 for specific concerns like hot flashes.)

Or if you meet the criteria for sleep apnea, your doctor might send you to a sleep specialist for further testing (like a sleep study to see what your breathing is like at night). From there, treatment typically includes getting fitted for a special device (like a CPAP machine) that keeps your airway open while you’re asleep. With thyroid issues, you might be referred to an endocrinologist for more testing and diagnosis.

The important thing is to try and see your doctor to understand what’s going on and how to get help. Soon, you won’t have to sweat it—literally.