Night sweats happen for reasons ranging from a warm bedroom to underlying medical conditions. Some degree of sweating during sleep is normal because your body actively lowers its core temperature as part of the sleep cycle. But when you wake up drenched, soaking through your sheets or needing to change clothes, something beyond normal cooling is usually at play.
Your Body Cools Itself During Sleep
Your brain’s internal thermostat, a region called the preoptic hypothalamus, controls both sleep initiation and body temperature. About two hours before you fall asleep, your core temperature starts dropping. Once you enter deep sleep, your brain widens blood vessels near the skin’s surface to release heat, which lowers your core and brain temperature further. This is why your hands and feet sometimes feel warm at bedtime: blood is being pushed to the surface to radiate heat away.
This cooling process naturally produces some moisture on the skin. It’s the same mechanism as daytime sweating, just quieter. Most people don’t notice it. But if your bedroom is too warm, your bedding traps heat, or something internal is amplifying the signal, the sweating becomes noticeable or disruptive.
A Too-Warm Sleep Environment
The simplest and most common reason for sweating at night is sleeping in conditions that are too hot. The ideal bedroom temperature for sleep is between 60 and 68°F (roughly 15 to 20°C). Heavy comforters, memory foam mattresses that trap body heat, and synthetic pajamas all raise your skin temperature and force your body to sweat more aggressively to compensate. Before investigating medical causes, it’s worth ruling out your sleep environment first.
Hormonal Changes and Menopause
Estrogen plays a direct role in how the brain regulates temperature. Neurons in the hypothalamus that control heat dissipation are sensitive to estrogen levels. When estrogen drops during perimenopause and menopause, these neurons misfire, essentially telling the body it’s overheating when it isn’t. The result is a sudden burst of vasodilation and sweating, commonly called a hot flash. When this happens during sleep, it produces the classic drenching night sweat that wakes you up.
This isn’t just discomfort. The sweating episodes fragment sleep, leading to fatigue and mood changes during the day. Night sweats from menopause can persist for years, though they tend to be most intense in the first year or two after periods stop.
Medications, Especially Antidepressants
Certain medications cause night sweats as a side effect, and antidepressants are among the most common culprits. Between 5 and 14% of people taking antidepressants experience excessive sweating. The two most widely prescribed classes, SSRIs and SNRIs, both carry a roughly threefold increased risk of sweating compared to placebo.
Among SSRIs, sertraline carries the highest risk, with nearly six times the rate of sweating compared to placebo. Paroxetine, escitalopram, citalopram, and fluoxetine all show elevated risk as well. Among SNRIs, duloxetine and venlafaxine are the most likely to cause sweating. A few antidepressants appear not to increase the risk, including bupropion and vortioxetine. About 2% of people on antidepressants find the sweating bothersome enough to stop the medication.
Other drugs linked to night sweats include hormone therapies, some blood pressure medications, and over-the-counter fever reducers like aspirin and acetaminophen (which can trigger rebound sweating as they wear off).
Alcohol and Blood Sugar Drops
Alcohol is a surprisingly common trigger. Drinking widens blood vessels in the skin and raises heart rate, both of which promote sweating. Alcohol also disrupts sleep architecture, meaning you spend more time in lighter, less stable sleep stages where your body’s temperature regulation is less efficient. Even moderate drinking in the evening can produce noticeable sweating a few hours later as your body metabolizes the alcohol.
Low blood sugar, or hypoglycemia, is another metabolic trigger. When blood sugar drops during the night, the body releases adrenaline and related stress hormones to push glucose back up. These hormones cause sweating, a racing heartbeat, trembling, and anxiety. This is most relevant for people with diabetes who take insulin or certain oral medications, but it can also occur in people who go to bed after heavy drinking or prolonged fasting, both of which can cause blood sugar to dip overnight.
Sleep Apnea
Obstructive sleep apnea, a condition where the airway repeatedly collapses during sleep, is strongly linked to night sweats. In one study, 31% of people with sleep apnea reported frequent night sweats (three or more times per week), compared to just 11% of the general population. Each time the airway closes, the body mounts a stress response to restart breathing, which activates the sympathetic nervous system and triggers sweating.
The connection is strong enough that treating sleep apnea with a PAP device cut the rate of frequent sweating from 33% down to about 12%, essentially matching the general population. If you snore heavily, wake up gasping, or feel exhausted despite a full night’s sleep, sleep apnea may be the hidden cause of your night sweats.
Infections
Infections are a classic medical cause of night sweats, particularly chronic or slow-burning ones. Tuberculosis is the textbook example: drenching night sweats are one of its hallmark symptoms. Other infections associated with night sweats include endocarditis (an infection of the heart’s inner lining), HIV, brucellosis, bone infections, and fungal infections like valley fever. In these cases, the immune system’s inflammatory response resets the body’s thermostat, producing fever and sweating that tend to be worst at night when body temperature naturally fluctuates.
Lymphoma and Other Cancers
Night sweats are one of three “B symptoms” used to stage Hodgkin lymphoma and some non-Hodgkin lymphomas. The other two are unexplained fever and unintentional weight loss. The night sweats associated with lymphoma are distinctive: they’re drenching, meaning you need to change your bedclothes. They tend to recur night after night and are accompanied by other signs like swollen lymph nodes, persistent fatigue, or losing weight without trying.
Cancer-related night sweats are uncommon relative to all the other causes on this list. But their severity and persistence set them apart from sweating caused by a warm room or a glass of wine.
Patterns Worth Paying Attention To
Occasional night sweats on a hot summer night or after a few drinks are not concerning. The patterns that warrant a closer look are sweating that happens regularly, disrupts your sleep, or comes with other symptoms like fever, unexplained weight loss, a persistent cough, or localized pain. Night sweats that begin well after menopause has ended also deserve investigation, since they suggest a cause other than hormonal changes.
If you’re trying to pin down the cause, keeping a simple log can help. Track what you ate and drank, your bedroom temperature, any medications you take, and whether you had other symptoms. This kind of record makes it far easier for a clinician to narrow down the possibilities if your sweating turns out to need medical attention.