Sweating during sleep is surprisingly common, and in most cases the cause is something fixable: your bedroom is too warm, your bedding traps heat, or your body is reacting to stress, hormones, or medication. True night sweats, the kind that soak through your sheets and wake you up, affect a significant portion of adults and can signal anything from an overheated room to an underlying medical condition worth investigating.
The key distinction is between sweating because your sleep environment is too hot and sweating regardless of temperature. If you kick off the covers, turn on a fan, and still wake up drenched, something internal is driving it.
Your Bedroom May Be Too Warm
The simplest explanation is often the right one. Your body temperature naturally drops during sleep, and if your environment fights that process, you sweat. The ideal bedroom temperature for sleep is between 60 and 67°F (15 to 19°C). Anything above 70°F is considered too hot and will likely cause restlessness and sweating. High humidity compounds the problem because sweat can’t evaporate efficiently, so your body keeps producing more of it.
Your bedding matters too. Memory foam mattresses and synthetic sheets trap heat against your body. Fabrics like bamboo viscose and Tencel (made from eucalyptus) actively pull moisture away from your skin and allow airflow. If you sleep hot, switching your sheets and using a breathable mattress topper can make a noticeable difference before you consider any medical explanations.
Hormonal Changes Are the Most Common Medical Cause
Hormones like estrogen and progesterone help your body regulate its internal thermostat. When levels rise or fall, your brain can lose its ability to keep you at a stable temperature, and it responds by triggering sweat to cool you down. This is the same mechanism behind hot flashes.
Perimenopause and menopause are the most frequent hormonal triggers. Night sweats can begin years before periods stop entirely, catching many women off guard. But hormonal shifts aren’t exclusive to menopause. Pregnancy, the menstrual cycle, thyroid disorders (particularly an overactive thyroid), and low testosterone in men can all disrupt temperature regulation during sleep. If your night sweats follow a pattern tied to your cycle, or if they started alongside other symptoms like fatigue, weight changes, or mood shifts, hormones are a strong suspect.
Medications That Cause Night Sweats
Several common medications list excessive sweating as a side effect, and it often shows up at night. Antidepressants are among the most frequent culprits. Between 3% and 19% of people taking SSRIs (a widely prescribed class of antidepressants) experience excessive sweating, depending on the specific drug. Other classes of antidepressants carry similar rates.
Beyond antidepressants, medications for diabetes, hormone therapy drugs, steroids, and some pain relievers can trigger night sweats. If your sweating started or worsened after beginning a new medication, that timing is worth noting. Don’t stop a medication on your own, but it’s a conversation worth having with whoever prescribed it, because alternatives or dosage adjustments often exist.
Stress and Anxiety Activate Your Sweat Glands
The same stress response that makes your palms clammy during a difficult conversation can operate while you sleep. Anxiety disorders and chronic stress elevate your heart rate, which raises your body temperature, which triggers sweating. This happens during the day too, but you may not notice it as much because you’re moving around and your environment is better ventilated.
Panic attacks can also occur during sleep, sometimes without fully waking you. You might not remember the episode itself, just the aftermath: soaked sheets, a racing heart, and a sense of unease. If you’re going through a stressful period and your night sweats are new, the connection is likely direct.
Sleep Apnea and Nighttime Sweating
Obstructive sleep apnea, a condition where your airway repeatedly closes during sleep, is an underrecognized cause of night sweats. When breathing stops, your body releases cortisol (the stress hormone), which raises your body temperature. Research from an Icelandic sleep study found that untreated sleep apnea patients had measurably higher sweating levels, and both sweating and blood pressure decreased with treatment.
The clue here is that sleep apnea rarely shows up as sweating alone. Loud snoring, gasping during sleep, daytime exhaustion despite a full night’s rest, and morning headaches are common companions. If your partner has noticed you snoring heavily or pausing your breathing, sleep apnea could be behind both your fatigue and your sweating.
Infections and Immune Responses
Your body raises its temperature to fight infections, and night sweats can be part of that process. Common infections like the flu or a sinus infection can cause temporary night sweats that resolve as you recover. More persistent infections, including tuberculosis and certain bacterial infections, are known to cause drenching night sweats that last weeks or longer.
HIV is another infection where night sweats are a recognized symptom, particularly in the early acute phase. These sweats tend to be severe and persistent rather than occasional.
When Night Sweats May Signal Something Serious
In rare cases, persistent night sweats are an early sign of certain cancers, particularly lymphoma and leukemia. This is not the most likely explanation for your sweating, but it’s worth knowing the warning signs that prompt doctors to investigate further.
The red flags that raise concern for malignancy or serious infection are specific: unexplained weight loss greater than 5% of your body weight over six to twelve months, recurring fevers, and swollen lymph nodes that persist for more than four to six weeks. Night sweats alone, without these accompanying symptoms, rarely point to cancer. But night sweats combined with any of those signs warrants prompt evaluation.
Practical Steps to Reduce Night Sweats
Start with your environment. Set your thermostat between 60 and 67°F. Switch to breathable bedding made from bamboo or Tencel rather than synthetic materials. Use a fan or open a window to improve airflow. Sleep in lightweight, loose clothing, or skip pajamas entirely.
Avoid known triggers in the hours before bed. Alcohol, spicy food, caffeine, and heavy meals all raise your core body temperature. Exercise is great for sleep quality overall, but finishing an intense workout less than two or three hours before bed can leave your body still cooling down when you’re trying to fall asleep.
If those changes don’t help, start tracking your sweats. Note the frequency, severity, and any patterns: time of month, new medications, stressful periods, accompanying symptoms. That record becomes extremely useful if you end up discussing it with a doctor, because “I sweat at night” is vague, while “I’ve soaked through my sheets four nights a week for the past two months, and I’ve also lost weight without trying” gives a clinician something concrete to work with.