Some sweating during sleep is completely normal for men. Your brain actually lowers its temperature “set point” when you fall asleep, similar to turning down a thermostat, and it uses sweating as one of the tools to cool your body down to that new target. But if you’re waking up drenched, soaking through shirts or sheets on a regular basis, something beyond normal thermoregulation is likely at play. The causes range from simple bedroom conditions to hormonal shifts, medications, and occasionally serious medical issues worth investigating.
Why Your Body Sweats During Sleep
Your core body temperature follows a 24-hour cycle. It peaks in the late afternoon and drops to its lowest point during the middle of the night. Research published in the Journal of Applied Physiology found that this overnight temperature drop isn’t just passive cooling. It’s an actively regulated process: your brain deliberately lowers its thermostat setting during your habitual sleeping hours and triggers sweating to hit that lower target. In a comfortable room, your body can’t shed enough heat through skin alone, so sweating kicks in to bridge the gap.
This means some degree of nighttime sweating is built into human biology. The amount varies based on your body composition, metabolism, and how warm your sleeping environment is. What separates normal sleep sweating from a problem is frequency, severity, and whether it disrupts your rest.
Bedroom Setup and Habits
Before looking at medical causes, it’s worth ruling out the obvious. Heavy blankets, memory foam mattresses (which trap heat), warm room temperatures, and synthetic pajamas all increase how much you sweat overnight. A bedroom temperature between 60 and 67°F tends to work best for most people. Sleeping in moisture-wicking fabrics or lighter bedding often makes a noticeable difference.
Alcohol is another common and underappreciated trigger. Drinking widens blood vessels in your skin and increases your heart rate, both of which ramp up heat loss and perspiration. Even moderate drinking in the evening can produce noticeably sweatier nights. Spicy food close to bedtime has a similar, though usually milder, effect.
Sleep Apnea and Night Sweats
Obstructive sleep apnea, where your airway repeatedly collapses during sleep, is one of the most common medical causes of night sweats in men and one of the most frequently overlooked. A study published in the European Respiratory Journal found that 31% of people with obstructive sleep apnea reported frequent night sweats (three or more times per week), compared to just 11% of the general population. That’s nearly a threefold increase.
The connection makes physiological sense. Each time your airway closes, your body mounts a stress response to wake you up enough to resume breathing. That repeated fight-or-flight activation drives up heart rate and triggers sweating. If your night sweats come with loud snoring, gasping during sleep, morning headaches, or daytime exhaustion, sleep apnea is a strong possibility. Treating it, typically with a CPAP machine, often resolves the sweating along with the other symptoms.
Hormonal Changes in Men
Testosterone levels gradually decline by about 1% per year after age 40. Most men maintain levels high enough that this doesn’t cause symptoms, but when testosterone drops significantly, night sweats and hot flashes can result. The mechanism involves the hypothalamus, the brain’s temperature control center. Low testosterone appears to destabilize it, causing it to misread your body temperature as too warm. The brain then sends signals to widen blood vessels in the skin, producing a sudden flush of warmth, followed quickly by a cold, clammy sweat as the body overcorrects.
This is most dramatic in men receiving hormone-blocking therapy for prostate cancer, where testosterone is suppressed to very low levels. But it can also occur in men with naturally low testosterone from other causes. If night sweats started alongside low energy, reduced sex drive, mood changes, or difficulty concentrating, a testosterone check is reasonable.
An overactive thyroid gland is another hormonal cause. It revs up your metabolism broadly, producing heat intolerance, weight loss despite normal appetite, a rapid heartbeat, and sweating that often worsens at night.
Medications That Cause Night Sweats
Antidepressants are among the most common medication triggers. Roughly 22% of people taking them experience excessive sweating as a side effect, and this frequently shows up at night. SSRIs and older tricyclic antidepressants are both implicated. If your night sweats started around the same time you began or changed an antidepressant, the timing is probably not a coincidence. Options exist for managing this side effect without stopping the medication, so it’s worth raising with whoever prescribed it.
Other medications linked to night sweats include fever reducers like aspirin and acetaminophen (which can trigger rebound sweating as they wear off), blood pressure medications, and hormone therapies. Opioid withdrawal also commonly produces drenching night sweats.
Low Blood Sugar Overnight
For men with diabetes, particularly those using insulin, nocturnal hypoglycemia is a specific and important cause. When blood sugar drops below 70 mg/dL during sleep, your body releases stress hormones to raise it back up, and one result is hot, clammy sweating. You might also wake with a headache, feel groggy, or notice your sheets are damp without feeling like you had a nightmare or were too warm. If you manage diabetes and regularly wake up sweaty, checking your blood sugar when it happens (or using a continuous glucose monitor) can confirm whether this is the cause.
Infections and Immune Conditions
Night sweats are a hallmark symptom of several infections, most notably tuberculosis. In its active form, TB typically causes night sweats several times per week along with a persistent cough, weight loss, and low-grade fevers. HIV can also produce recurrent night sweats, sometimes as one of the earliest symptoms. Other infections where night sweats are a core feature include infectious mononucleosis (especially during the acute phase), fungal infections like histoplasmosis, and endocarditis, an infection of the heart valves that causes sweating tied to waves of bacteria entering the bloodstream overnight.
Lymphoma, a cancer of the lymphatic system, is the malignancy most strongly associated with night sweats. The Mayo Clinic describes the pattern as “drenching night sweats,” often accompanied by unexplained weight loss, persistent fatigue, and painless swelling of lymph nodes in the neck, armpits, or groin. Not every case of night sweats points to cancer, but when sweats are severe enough to soak through clothing and occur alongside these other symptoms, evaluation is important.
Anxiety and Stress
Generalized anxiety disorder and chronic stress both activate your sympathetic nervous system, the same fight-or-flight system responsible for stress sweating during the day. This activation doesn’t always shut off at night. Men dealing with high stress, unresolved anxiety, or PTSD often report night sweats that don’t have an obvious physical trigger. The sweating may coincide with vivid dreams or restless sleep, or it may happen without any awareness of disrupted sleep at all.
How to Tell What’s Causing Yours
Pattern recognition helps narrow the cause. Night sweats that happen only after drinking, only on certain nights, or only when your bedroom is warm point toward environmental or lifestyle factors. Sweats that started when you began a new medication have an obvious suspect. Sweats that are persistent, happen multiple times per week regardless of conditions, and come with other symptoms like weight loss, fevers, fatigue, or swollen lymph nodes warrant medical evaluation.
Your doctor will typically start with a detailed history and physical exam. Lab work isn’t always necessary unless the pattern suggests an underlying condition. If sleep apnea is suspected, a sleep study is the standard next step. For hormonal concerns, blood tests for testosterone and thyroid function are straightforward. The key information to bring to that conversation is how often the sweats occur, how severe they are (damp skin vs. soaked sheets), when they started, and any other symptoms you’ve noticed alongside them.