Night sweats are surprisingly common, and in most cases the cause is something straightforward: your room is too warm, you had a drink before bed, or your body is reacting to a medication or hormonal shift. But when sweating during sleep happens repeatedly and soaks through your clothes or sheets, it’s worth understanding what might be driving it. The causes range from simple environmental fixes to medical conditions that benefit from treatment.
Your Sleep Environment May Be the Simplest Explanation
Before looking at medical causes, the first thing to rule out is your bedroom setup. Sleep experts at the Cleveland Clinic recommend keeping your bedroom between 60 and 67°F (15 to 19°C). Many people sleep in rooms well above that range, especially in warmer months or with heavy bedding. Memory foam mattresses, synthetic sheets, and thick comforters trap heat against your body, and your core temperature naturally dips during sleep. If your environment prevents that cooldown, you sweat.
Moisture-wicking sheets made from athletic-style fabrics can help more than standard cotton, which absorbs moisture but holds it against your skin. The International Hyperhidrosis Society specifically recommends avoiding non-breathable synthetics like polyester and upgrading to quick-drying bedding designed for night sweats. Lightweight, breathable sleepwear made from the same moisture-wicking materials used in exercise clothing is another practical swap.
Alcohol, Caffeine, and Spicy Food
A glass of wine or a spicy meal close to bedtime can trigger sweating a few hours into sleep. Alcohol is the most common culprit. It relaxes your airways (which can make breathing harder) while simultaneously acting as a stimulant that raises your heart rate. Both effects increase your body temperature. Spicy foods and caffeine work similarly, raising your metabolic heat production right when your body is trying to cool down for sleep. If your night sweats happen mainly on nights when you’ve had any of these, you likely have your answer.
Hormonal Changes and Menopause
For people going through perimenopause or menopause, night sweats are one of the most recognizable symptoms. Declining estrogen disrupts the brain’s internal thermostat, a region in the hypothalamus that regulates body temperature. Normally, your brain tolerates minor temperature fluctuations without triggering a sweat response. But when estrogen drops, the “thermoneutral zone” narrows dramatically, to as little as 0.4°C. That means even a tiny rise in body temperature, one your brain would normally ignore, can set off a full-blown heat-dissipation response: blood vessels dilate, your skin flushes, and you sweat.
These episodes can happen during the day (hot flashes) or at night (night sweats), and they vary widely in intensity. Some people experience mild dampness, while others wake up needing to change their sheets. This pattern can begin years before periods stop entirely and may continue for several years afterward.
Medications That Cause Sweating
Several common medications list sweating as a side effect, and the timing often clusters at night. Antidepressants, particularly SSRIs like citalopram, escitalopram, fluoxetine, and paroxetine, affect serotonin signaling in the hypothalamus, which can interfere with temperature regulation. If your night sweats started around the same time you began a new medication, that connection is worth flagging.
Corticosteroids like prednisone and dexamethasone also cause sweating by disrupting hormonal feedback loops that regulate body temperature. Other medications linked to night sweats include certain blood pressure drugs, diabetes medications (especially if blood sugar drops overnight), and hormone therapies. Stopping or switching a medication can sometimes resolve the issue entirely, but that’s a conversation to have with whoever prescribed it.
Anxiety, Depression, and Stress
Mood disorders have a strong and underappreciated connection to night sweats. Panic attacks can happen during sleep, triggering a surge of adrenaline that raises heart rate, body temperature, and sweating. Depression and post-traumatic stress disorder are also independently associated with night sweats, even without a clear panic episode. The mechanism involves your sympathetic nervous system, the fight-or-flight branch, staying more active than it should during sleep. If you’re dealing with persistent stress, anxiety, or mood changes alongside your night sweats, the two are likely related.
Sleep Apnea
Obstructive sleep apnea, where your airway partially or fully closes during sleep, is a commonly overlooked cause of night sweats. When your body struggles to breathe, oxygen levels drop and you wake briefly, often without realizing it. These frequent awakenings and the accompanying physical effort ramp up your sympathetic nervous system, which drives sweating. If you also snore, wake up with headaches, or feel exhausted despite a full night of sleep, sleep apnea is worth investigating. Treating it often resolves the sweating.
Thyroid Problems
An overactive thyroid (hyperthyroidism) speeds up your metabolism, which raises your baseline body temperature and causes generalized sweating throughout the day and night. Night sweats from hyperthyroidism rarely happen in isolation. You’d typically also notice a racing heart, unexplained weight loss, anxiety, trembling hands, diarrhea, or sensitivity to heat. If several of those sound familiar, a simple blood test can confirm or rule it out.
Infections
Certain infections cause sweating that’s most noticeable at night, likely because of small, undetected spikes in body temperature during sleep. Tuberculosis is the classic example, though it’s uncommon in many countries today. Bacterial heart valve infections (endocarditis) produce night sweats related to waves of bacteria entering the bloodstream, causing nocturnal fevers. HIV, fungal infections, and abscesses can also present this way. Infection-related night sweats typically come with other symptoms: fever, fatigue, weight loss, or feeling generally unwell.
Other Medical Conditions
Gastroesophageal reflux disease (GERD) is associated with night sweats, particularly because acid reflux worsens when you lie flat. Obesity increases the likelihood of night sweats both because excess body fat insulates heat and because it raises the risk of sleep apnea. Diabetes can cause overnight sweating when blood sugar drops too low during sleep, especially in people taking insulin or certain oral medications. Restless legs syndrome has also been linked to nighttime sweating, likely through the same mechanism of frequent micro-awakenings that activates the nervous system.
When Night Sweats Signal Something Serious
In rare cases, persistent night sweats can be an early sign of lymphoma or another cancer. The pattern that warrants attention is a combination of symptoms sometimes called “B symptoms”: drenching night sweats alongside unexplained weight loss and recurring fevers. With non-Hodgkin lymphoma, you might also notice painless swelling in your neck, armpit, or groin, shortness of breath, or persistent itchy skin. Research on Hodgkin’s disease found that sweating as the only symptom correlated with undetected rises in body temperature from the disease itself.
These cancers are uncommon, and night sweats alone, without other symptoms, are rarely the first sign of malignancy. But if you’re experiencing soaking sweats that persist for weeks, have lost weight without trying, or have developed new lumps or fevers, those symptoms together deserve prompt evaluation.
Narrowing Down Your Cause
The most useful thing you can do is look for patterns. Track when your night sweats happen and what preceded them: alcohol, a heavy meal, a stressful day, a new medication, your menstrual cycle. Note whether you have any accompanying symptoms like weight changes, mood shifts, snoring, or heartburn. A clear pattern often points directly to the cause. Night sweats that happen occasionally and line up with an obvious trigger, like a warm room or a few drinks, are almost always benign. Night sweats that are persistent, drenching, and accompanied by other unexplained symptoms are the ones worth bringing to a doctor with your observations in hand.