Sweating during sleep is usually your body’s normal response to being too warm, but it can also signal something worth paying attention to. Most of the time, the cause is straightforward: your bedroom is too hot, your bedding is too heavy, or something you ate or drank before bed raised your body temperature. When night sweats happen repeatedly without an obvious environmental explanation, that’s when other factors come into play.
How Your Body Regulates Temperature During Sleep
Your brain’s internal thermostat naturally lowers your body temperature as you fall asleep. During the deeper stages of sleep, your core temperature drops, and blood vessels near the skin’s surface widen to release heat. This cooling process is essential for staying asleep. If anything interferes with it, your body compensates by sweating.
Warm bedding actually helps trigger this sleep-cooling cycle by creating a warm microclimate around your skin, which signals your brain to begin the process. But if your environment is too warm, the system overshoots and you wake up damp. The ideal bedroom temperature for sleep is 60 to 67°F (15 to 19°C), according to Cleveland Clinic. If your room runs warmer than that, or you’re sleeping under heavy blankets with a partner and a pet, the simplest explanation is often the right one.
Common Lifestyle Triggers
Before looking at medical causes, it’s worth ruling out the everyday habits that commonly cause sleep sweating.
Alcohol: Drinking before bed increases your heart rate and widens blood vessels in your skin, both of which trigger perspiration. Even moderate drinking can do this. If you’re physically dependent on alcohol, withdrawal itself can cause drenching night sweats. Some people also have a genetic variation that prevents their body from properly breaking down toxins in alcohol, making them especially prone to sweating after even small amounts.
Spicy food and heavy meals: Eating close to bedtime raises your metabolic rate and core temperature. Spicy foods in particular activate heat receptors in your body, which can push your thermoregulation system into overdrive while you sleep.
Exercise timing: Working out within two to three hours of bedtime leaves your core temperature elevated. Your body may still be trying to cool down after you fall asleep, producing noticeable sweat.
Medications That Cause Night Sweats
If you started sweating in your sleep around the same time you began a new medication, the drug is a likely culprit. Antidepressants are one of the most common offenders. SSRIs (like sertraline and fluoxetine), SNRIs (like venlafaxine), tricyclic antidepressants, and several other classes of psychiatric medications all interfere with the brain chemicals that help regulate sweating. This is a well-recognized side effect across nearly every category of antidepressant.
Other medications linked to night sweats include some blood pressure drugs (particularly beta blockers), hormone therapies, steroids, and certain diabetes medications that can cause blood sugar to drop too low overnight. If you suspect a medication is the cause, it’s worth bringing it up at your next appointment rather than stopping anything on your own.
Hormonal Changes
For women in their 40s and 50s, hormonal shifts are one of the most common reasons for nighttime sweating. An estimated 35% to 50% of women in perimenopause experience sudden waves of body heat with sweating and flushing that last 5 to 10 minutes. These episodes happen during the day (hot flashes) and at night (night sweats), and they can range from mildly annoying to sleep-disrupting for years.
Night sweats from perimenopause and menopause are caused by fluctuating estrogen levels, which make the brain’s temperature-control center more sensitive. Even a tiny increase in core temperature can trigger a full sweat response. Men can experience something similar when testosterone levels drop, though it’s less common and usually less intense.
An overactive thyroid gland is another hormonal cause. It speeds up your metabolism, raises your baseline body temperature, and can make you sweat around the clock, including during sleep.
Anxiety and Nocturnal Panic Attacks
Stress and anxiety keep your nervous system in a heightened state, and that doesn’t always shut off when you fall asleep. Some people experience nocturnal panic attacks, which jolt you awake with a racing heart, shortness of breath, and profuse sweating. These episodes happen without any obvious trigger during sleep, and they can feel alarming because you wake up mid-symptom without understanding what caused it.
Even without full panic attacks, chronic stress and anxiety raise your baseline levels of stress hormones, which can increase sweating throughout the night. If you’ve been under significant stress or dealing with anxiety, this is a common and often overlooked explanation.
Sleep Apnea
Obstructive sleep apnea, a condition where your airway repeatedly collapses during sleep, is an underappreciated cause of night sweats. Each time your airway closes, your oxygen levels drop and your brain pulls you out of deep sleep to restart breathing. This triggers a stress response that includes sweating. People with sleep apnea often also snore loudly, wake up frequently to urinate, and feel unrested in the morning. If any of those sound familiar alongside the sweating, sleep apnea is worth investigating.
Medical Conditions to Be Aware Of
In a small percentage of cases, persistent night sweats point to an underlying medical condition. Infections are one category: anything from a lingering viral illness to more serious infections like tuberculosis can cause recurring night sweats, usually alongside fever. Low blood sugar overnight (common in people with diabetes who take insulin) triggers a stress hormone surge that produces sweating, sometimes without waking you up.
The concern most people have when they search this topic is cancer, and it’s worth addressing directly. Certain blood cancers, particularly lymphoma and leukemia, can cause drenching night sweats as an early symptom. But cancer-related night sweats have a specific pattern: they’re typically severe enough to soak through your clothes and sheets, they happen repeatedly over weeks, and they come alongside other symptoms like unexplained weight loss, persistent fever, or unusual fatigue. Waking up a bit sweaty once or twice after a warm night is not the same thing.
The red flags that warrant a call to your doctor are: night sweats that are drenching and recurrent, sweats accompanied by unexplained weight loss of more than a few pounds, a persistent fever you can’t explain, or night sweats that started suddenly and have no clear environmental or lifestyle cause. A basic workup typically involves blood tests to check your thyroid function, blood sugar, signs of infection, and blood cell counts. From there, your doctor can narrow things down based on what comes back.
Simple Fixes to Try First
If your night sweats are occasional and you don’t have other concerning symptoms, a few changes can make a meaningful difference. Lower your thermostat to the 60 to 67°F range. Switch to lighter, moisture-wicking bedding and sleepwear. Avoid alcohol, spicy foods, and heavy meals within three hours of bedtime. Move your workout earlier in the day if you’ve been exercising at night.
If the sweating continues after you’ve optimized your sleep environment, start keeping a simple log: when it happens, what you ate or drank, what medications you took, and how severe it was. This kind of pattern tracking is surprisingly useful, both for identifying your own triggers and for giving your doctor something concrete to work with if you do need to be evaluated.