Sweating in your sleep falls into two categories: overheating because your room is too warm or your blankets are too heavy, and true night sweats, which are episodes of generalized sweating that can range from moderate dampness to drenching episodes that force you to change your sheets and clothes. If you’re regularly waking up soaked, something beyond your bedroom setup is likely going on.
Your Bedroom May Be Too Warm
The simplest explanation is often the right one. The ideal sleeping temperature for adults is between 60 and 67°F (15 to 19°C). Anything above 70°F is considered too hot and will increase restlessness and sweating. High humidity compounds the problem because your sweat can’t evaporate efficiently, so your body keeps producing more of it.
Synthetic bedding, memory foam mattresses, and heavy comforters all trap heat close to your body. If your sweating started around the time you changed your mattress, bedding, or sleeping arrangement, that’s worth noting. Try sleeping in lighter, breathable fabrics (both pajamas and sheets), dropping your thermostat below 68°F, and using a fan for air circulation. If the sweating stops, you’ve found your answer.
Hormonal Shifts Are the Most Common Medical Cause
Estrogen plays a central role in how your brain regulates body temperature. When estrogen levels drop or fluctuate sharply, the brain’s internal thermostat becomes more sensitive, narrowing the temperature range your body considers “normal.” Small increases in core temperature that would normally go unnoticed instead trigger a full cooling response: blood vessels in the skin dilate, and sweat glands activate. This is the mechanism behind hot flashes and night sweats during perimenopause and menopause.
The same basic process happens after giving birth. Postpartum night sweats are most intense during the first two weeks after delivery and typically resolve within a few weeks as hormone levels stabilize. If you’re breastfeeding, low estrogen levels can extend night sweats beyond that window. Sweating that persists longer than three weeks postpartum is worth mentioning to your provider.
Hormonal night sweats aren’t exclusive to women. Men with low testosterone can experience them too, as testosterone influences thermoregulation through similar pathways.
Medications That Cause Night Sweats
Up to 22% of people taking antidepressants experience excessive sweating as a side effect. This happens across all major classes of antidepressants, not just one type. If your night sweats started within weeks of beginning or adjusting a medication, the timing is a strong clue.
Other common culprits include medications for diabetes that can cause low blood sugar overnight (which triggers sweating as part of the stress response), hormone-blocking treatments used in cancer care, fever reducers like aspirin or acetaminophen (paradoxically, as they wear off, your body may sweat to cool itself), and some blood pressure medications. If you suspect a medication connection, don’t stop taking it on your own, but do bring it up with your prescriber. Often, adjusting the dose or switching to an alternative resolves the problem.
Sleep Apnea and Night Sweats
Obstructive sleep apnea, where your airway repeatedly collapses during sleep, is an underrecognized cause of night sweats. Each time your breathing stops, your body mounts a stress response that includes a surge of adrenaline. That surge raises your heart rate, constricts blood vessels, and triggers sweating. Research from the Mayo Clinic found that severe hot flashes and night sweats in middle-aged women were linked to intermediate or high risk of sleep apnea, yet 65% of those at elevated risk remained undiagnosed two years later.
If your night sweats come with loud snoring, gasping or choking during sleep, daytime fatigue despite a full night’s rest, or morning headaches, sleep apnea is worth investigating. A sleep study can confirm or rule it out, and treatment often eliminates the sweating along with the other symptoms.
Infections and Immune Responses
Your body raises its temperature to fight infections, and sweating is how it brings that temperature back down. Viral illnesses, bacterial infections, and even mild infections you might not otherwise notice can produce night sweats. Tuberculosis is the classic textbook example, but common infections like urinary tract infections, sinus infections, or endocarditis (an infection of the heart valves) can cause them too.
Night sweats from infections almost always come with other symptoms: fever or chills, fatigue, body aches, or feeling generally unwell. If you’ve been sick and the sweating tracks with your illness, it will likely resolve as you recover.
When Night Sweats Signal Something Serious
Lymphoma and certain other cancers can cause what doctors call “drenching” night sweats, the kind where you wake up and your sleepwear is completely soaked through. In lymphoma, these sweats are considered a “B symptom” alongside unexplained weight loss (typically more than 10% of body weight over six months), persistent fevers, and ongoing fatigue. Swollen lymph nodes in the neck, armpits, or groin may also be present.
To be clear, night sweats alone are far more likely to have a benign cause. But certain patterns warrant prompt medical attention. See your doctor if your night sweats happen regularly and wake you up, if they’re accompanied by unexplained weight loss, if you also have a persistent fever or chills, or if they’ve continued for several weeks without an obvious explanation like a warm bedroom or a known medication side effect.
Other Common Triggers
Alcohol, even in moderate amounts, causes blood vessels to dilate and can disrupt your body’s temperature regulation during sleep. A drink or two in the evening is enough to trigger sweating in some people, particularly as the body metabolizes the alcohol overnight. Spicy food close to bedtime has a similar vasodilating effect.
Anxiety and stress keep your sympathetic nervous system (your “fight or flight” system) activated. During sleep, this can manifest as sweating, a racing heart, or restless sleep even when you don’t recall feeling anxious. Chronic stress is especially likely to produce this pattern because the nervous system stays in a heightened state around the clock.
Hypoglycemia, or low blood sugar overnight, triggers sweating as part of the body’s alarm system. This is most relevant if you have diabetes or are on medications that affect blood sugar, but it can happen in anyone who goes to bed after heavy exercise without eating enough, or who skips dinner entirely.
Practical Steps to Reduce Night Sweats
Start with the controllable factors. Keep your bedroom between 60 and 67°F. Switch to cotton or moisture-wicking sheets and sleepwear. Avoid alcohol, caffeine, and spicy food within a few hours of bedtime. If you exercise in the evening, give your body at least two to three hours to cool down before sleep.
Keep a simple log for one to two weeks: note what you ate and drank, your bedroom temperature, what medications you took, and how severe the sweating was. Patterns often emerge quickly, and this information is invaluable if you end up seeing a doctor. A provider evaluating night sweats will typically ask about your medication list, menstrual history or hormonal status, recent infections, weight changes, and whether you snore or feel unrested in the morning. Having answers ready makes for a faster, more productive visit.