Sweating in your sleep is surprisingly common, and in most cases it comes down to something straightforward: your bedroom is too warm, your bedding traps heat, or your body is reacting to something you ate, drank, or took before bed. But when night sweats happen repeatedly, soak through your clothes or sheets, or show up alongside other symptoms, they can signal hormonal shifts, medication side effects, blood sugar drops, or less commonly, an underlying illness that needs attention.
Your Sleep Environment May Be the Simplest Explanation
The ideal bedroom temperature for sleep is between 60 and 67°F (15 to 19°C). Anything above that range makes it harder for your body to cool itself during the night, and sweating is the result. Heavy comforters, memory foam mattresses that retain heat, and synthetic pajamas that don’t breathe all compound the problem. Alcohol consumption before bed also raises your core temperature and dilates blood vessels near the skin, which can trigger sweating even in a cool room.
If you woke up sweaty once or twice and it hasn’t become a pattern, start here. Switch to moisture-wicking or quick-drying pajamas and sheets rather than standard cotton or non-breathable synthetics. Athletic-style fabrics designed to pull moisture away from skin are now made specifically for sleepwear and bedding. Lower the thermostat, use lighter layers you can kick off, and see if the problem disappears.
Hormonal Changes Are the Most Common Medical Cause
Hormones like estrogen and progesterone help your body regulate its internal thermostat. When their levels rise or fall sharply, your brain can misjudge your core temperature and trigger a cooling response, meaning a sudden flush of heat followed by sweating. This is the mechanism behind the hot flashes and night sweats that affect many women during perimenopause and menopause, but it’s not limited to those stages. Menstrual cycle fluctuations, pregnancy, and postpartum hormonal shifts can all produce the same effect.
Thyroid problems work through a similar pathway. An overactive thyroid speeds up your metabolism and raises your baseline body temperature, making you more likely to sweat at night. Conditions affecting other hormone-producing glands, including certain endocrine tumors and diabetes, can also interfere with temperature regulation in ways that show up as night sweats.
Medications, Especially Antidepressants
If you started or changed a medication recently and then began sweating at night, the two are likely connected. Antidepressants are the most well-documented culprit. Over 20% of people taking antidepressants experience excessive sweating as a side effect, and it occurs across all major classes of these drugs. This isn’t limited to one specific medication; it’s been reported with common prescriptions across the board.
Other medications that can cause night sweats include hormone therapies, drugs that lower blood sugar, steroids, and some pain relievers. If you suspect a medication is the cause, don’t stop taking it on your own. Your prescriber can often adjust the dose or switch you to an alternative that doesn’t have this effect.
Low Blood Sugar While You Sleep
When your blood sugar drops too low during the night, your body releases a burst of adrenaline to raise it back up. That adrenaline surge triggers sweating, a racing heart, and shakiness. You may wake up with damp sheets, feeling confused, tired, or hungry. This is most common in people with diabetes who take insulin, but it can happen to anyone. Eating a large, carbohydrate-heavy meal in the evening can cause your pancreas to overproduce insulin, leading to a delayed blood sugar crash hours later while you’re asleep. This is called reactive hypoglycemia.
If you’re waking up sweaty and also feeling shaky, disoriented, or ravenously hungry, blood sugar is worth investigating. A balanced evening meal with protein and fat alongside carbohydrates helps prevent the insulin spike that leads to a nighttime crash.
Infections and Illness
Your body raises its temperature to fight infections, and sweating is how it cools back down. Any illness that causes fever can produce night sweats, from a common cold to the flu. But certain infections are specifically associated with persistent, recurring night sweats even when you don’t feel obviously sick during the day. These include tuberculosis, endocarditis (an infection of the heart’s inner lining), HIV, brucellosis, and some fungal infections. Night sweats from these conditions tend to be drenching rather than mild, and they persist over weeks rather than resolving in a few days.
Recent travel, exposure to someone with tuberculosis, or new symptoms like a lingering cough, fever, or fatigue alongside the sweats all warrant a closer look from a healthcare provider.
When Night Sweats Could Signal Something Serious
Lymphoma and certain other cancers are a less common but important cause of night sweats. The sweating associated with lymphoma is typically described as “drenching,” meaning you wake up needing to change your clothes or sheets. It usually doesn’t occur in isolation. The classic combination is drenching night sweats, unexplained weight loss, and persistent fatigue, sometimes accompanied by painless swelling of lymph nodes in the neck, armpits, or groin and recurring fevers or chills.
Night sweats alone, without these other symptoms, are rarely a sign of cancer. But if you’ve had soaking sweats for more than a few weeks and you’ve also lost weight without trying, feel persistently exhausted, or notice swollen glands, those findings together deserve a medical evaluation. A doctor will typically start with blood work and imaging to rule out or identify the cause.
Practical Steps to Reduce Sleep Sweating
For the many cases where night sweats are annoying but not dangerous, a few changes can make a real difference:
- Cool your room. Aim for 60 to 67°F. A fan or air conditioning helps, but even cracking a window in cooler weather can be enough.
- Upgrade your bedding. Moisture-wicking sheets and pajamas designed for night sweats dry faster and pull sweat away from your skin. Avoid standard synthetic fabrics that trap heat.
- Layer strategically. Use lighter blankets you can remove during the night rather than one heavy comforter.
- Watch evening habits. Alcohol, spicy food, caffeine, and large carb-heavy meals close to bedtime all raise the likelihood of overnight sweating.
- Review your medications. If you started something new in the weeks before the sweating began, check whether night sweats are a known side effect.
If the sweating is mild, occasional, and resolves with environmental changes, it’s almost certainly nothing to worry about. If it’s persistent, drenching, or accompanied by weight loss, fever, pain, or fatigue, it’s your body telling you something more is going on.