Night sweats are repeated episodes of heavy sweating during sleep, enough to soak through your pajamas or bedding. If this keeps happening, it’s not just because your room is warm. While an overheated bedroom is the simplest explanation, persistent night sweats can stem from hormonal shifts, medications, stress, sleep disorders, or occasionally something more serious that needs medical attention.
Night Sweats vs. Sleeping Warm
There’s a difference between feeling a little damp and true night sweats. Clinically, night sweats mean sweating heavy enough that you need to change your clothes or sheets. Waking up slightly warm after piling on blankets doesn’t qualify. If you’re regularly drenching your bedding regardless of room temperature, something internal is driving it.
Your body naturally drops its core temperature during sleep, and sweating is one of the tools it uses. But when the system overshoots, whether because of a hormonal signal, a medication, or an illness, you end up waking in a pool of sweat. The key question is whether the cause is environmental (fixable tonight) or physiological (worth investigating further).
Hormonal Changes
Hormones play a central role in temperature regulation. When levels of estrogen, testosterone, or thyroid hormones rise or fall, your brain can lose its ability to keep your body at a comfortable temperature. It overreacts to small fluctuations and triggers a sweating response to cool you down, even when you don’t actually need cooling.
Menopause is the most common hormonal cause. The drop in estrogen disrupts the brain’s internal thermostat, producing hot flashes during the day and drenching sweats at night. Perimenopause (the years leading up to menopause) can trigger the same symptoms, sometimes before periods have even become irregular. An overactive thyroid gland can also rev up your metabolism and body heat, causing nighttime sweating alongside symptoms like a racing heart, weight loss, and feeling jittery.
Low testosterone in men is a less well-known but real trigger. It works through a similar mechanism: the hormonal shift destabilizes temperature control, and your body defaults to sweating.
Medications That Cause Sweating
If your night sweats started around the same time as a new prescription, the medication may be the culprit. Several common drug classes are linked to nighttime sweating:
- Antidepressants, particularly SSRIs, are among the most frequent offenders
- Blood pressure medications, including a class called angiotensin II receptor blockers
- Steroids used for inflammation or autoimmune conditions
- Thyroid hormone supplements, especially if the dose is slightly too high
- Hormone-related medications, including drugs used in breast cancer treatment and prostate cancer therapy
If you suspect a medication, don’t stop it on your own. But it’s worth flagging the timing with your prescriber, because a dose adjustment or alternative drug can sometimes resolve the problem entirely.
Anxiety and the Stress Response
Stress and anxiety don’t clock out when you fall asleep. Your body’s fight-or-flight system can stay activated overnight, keeping stress hormones elevated and your sweat glands engaged. People with anxiety disorders often notice that their night sweats worsen during high-stress periods, then improve when the stressor passes.
This type of sweating tends to come with other signs: trouble falling asleep, racing thoughts at bedtime, waking up with your heart pounding, or feeling unrested even after a full night. If that pattern sounds familiar, the sweating is likely a symptom of the anxiety rather than a separate problem.
Sleep Apnea
Obstructive sleep apnea, where your airway repeatedly collapses during sleep, is a surprisingly common cause of night sweats. Each time your breathing stops, your nervous system fires an alarm response that raises blood pressure and activates sweat glands. Research from an Icelandic sleep study found that untreated sleep apnea patients had measurably higher sweating activity, and both the sweating and elevated blood pressure decreased when they started using a breathing device (CPAP) during sleep.
If your night sweats come with loud snoring, gasping awake, morning headaches, or daytime exhaustion, sleep apnea is worth investigating. It’s one of the most treatable causes of night sweats, and fixing it improves far more than just the sweating.
Infections and Immune Responses
Your immune system raises body temperature to fight infections, and sweating is how your body brings that temperature back down. Short-term illnesses like the flu cause temporary night sweats that resolve on their own. But persistent, unexplained night sweats can signal a chronic or hidden infection.
Tuberculosis is historically one of the most well-known infectious causes. HIV, heart valve infections (endocarditis), and deep abscesses can also produce drenching sweats that persist for weeks. These are uncommon in otherwise healthy people, but they’re worth considering if night sweats are accompanied by fever, unexplained weight loss, or prolonged fatigue.
When Night Sweats Signal Something Serious
Certain cancers, particularly lymphoma and leukemia, list night sweats as an early symptom. In lymphoma, doctors look for a specific cluster called “B symptoms”: drenching night sweats, unexplained weight loss (typically more than 10% of body weight over six months), and recurring fevers. You might also notice painless swelling in your neck, armpits, or groin, persistent fatigue, itchy skin, or bone pain.
Night sweats alone, without these other symptoms, are rarely caused by cancer. But if you’re experiencing several of these together, and especially if the sweats are severe enough to soak your sheets night after night, it warrants a visit to your doctor for blood work and a physical exam.
Alcohol, Caffeine, and Spicy Food
What you consume in the evening directly affects how much you sweat overnight. Alcohol dilates blood vessels and disrupts your body’s temperature regulation, which is why a night of heavy drinking often ends in sweaty, fragmented sleep. Over time, regular heavy drinking makes the problem worse as your body struggles to recalibrate between drinking and withdrawal cycles.
Caffeine consumed too close to bedtime and spicy foods eaten at dinner can also raise your core temperature or stimulate your nervous system enough to trigger sweating. These are the easiest causes to test: cut them out for a week or two and see if the sweating improves.
Fixing Your Sleep Environment
Before pursuing medical causes, rule out the basics. The National Sleep Foundation recommends keeping your bedroom between 60 and 67°F (15.5 to 19.5°C) for optimal sleep. Some sleep researchers suggest an even narrower sweet spot of 60 to 65°F. A 2023 study of older adults found the most restful sleep occurred between 68 and 77°F, suggesting some individual variation, but cooler generally beats warmer for reducing sweat.
Beyond temperature, your bedding and sleepwear matter. Synthetic fabrics trap heat against your skin. Cotton or moisture-wicking materials let heat escape. Memory foam mattresses and thick mattress toppers can also retain body heat in ways that spring or hybrid mattresses don’t. High humidity makes everything worse because sweat can’t evaporate efficiently, so a fan or dehumidifier in a muggy bedroom can make a noticeable difference.
If you’ve optimized your environment, cut out evening alcohol and caffeine, and you’re still soaking through your sheets several times a week, that’s a sign the cause is internal. Keeping a simple log of when the sweating happens, how severe it is, and what else you notice (fever, weight changes, new medications, stress levels) gives your doctor useful information to narrow down the cause quickly.