Night sweats happen when your body produces enough sweat during sleep to soak through your clothes or sheets. While a too-warm bedroom is the most common culprit, recurring night sweats can also signal hormonal shifts, medication side effects, sleep disorders, or occasionally something more serious. Understanding the pattern of your sweating, how often it happens, and what else is going on in your body can help you figure out whether the fix is simple or worth investigating further.
Your Bedroom May Be Too Warm
The simplest explanation is often the right one. Your body temperature naturally drops during sleep as part of your circadian rhythm, and it needs a cool environment to do that effectively. If your bedroom is too warm, your body compensates by sweating. The recommended bedroom temperature for adults is 60 to 67°F (15 to 19°C), which feels cooler than most people expect. Heavy blankets, memory foam mattresses that trap heat, and synthetic pajamas can all push your body past its comfort zone even when the room itself seems fine.
If your night sweats are mild and don’t happen every night, adjusting your sleep environment is worth trying before looking for medical causes. Switch to breathable cotton or linen bedding, keep a fan running, and check your thermostat. If the sweating stops, you have your answer.
Hormonal Changes Are a Leading Cause
Hormones like estrogen and progesterone play a direct role in how your brain regulates body temperature. When those hormone levels rise or fall, your internal thermostat can misfire, triggering a wave of heat and sweating even when the room is cool. This is the same mechanism behind hot flashes, and it happens more often during sleep because your body is already working to lower its temperature.
Perimenopause and menopause are the most common hormonal triggers, affecting up to 80% of women during the transition. But hormonal night sweats aren’t exclusive to menopause. Pregnancy, the luteal phase of the menstrual cycle, and low testosterone in men can all cause the same response. Puberty is another common trigger that often goes unmentioned. If your night sweats track with other hormonal symptoms like irregular periods, mood changes, or fatigue, the connection is likely hormonal.
Medications That Cause Night Sweats
Several common medications list night sweats as a side effect, and this catches many people off guard. The most frequent offenders include:
- Antidepressants, particularly SSRIs and SNRIs, which affect the brain chemicals involved in temperature regulation
- Hormone therapy, including treatments for menopause, breast cancer, or prostate cancer
- Diabetes medications that lower blood sugar, since a blood sugar drop during the night triggers a stress response that includes sweating
- Methadone, used in opioid use disorder treatment
If your night sweats started around the same time you began a new medication or changed your dose, the timing is a strong clue. This doesn’t mean you should stop the medication on your own, but it’s worth flagging with whoever prescribed it. Dose adjustments or switching to a different drug in the same class can often solve the problem.
Sleep Apnea and Night Sweats
There’s a surprisingly strong link between obstructive sleep apnea and sweating at night. About 31% of people with sleep apnea report frequent night sweats (three or more times per week), compared to roughly 11% of the general population. The likely explanation is that when your airway repeatedly closes during sleep, your body goes into a stress response, your heart rate spikes, and you sweat.
The telling detail here is what happened in treatment studies. When people with sleep apnea used a CPAP machine consistently, their rate of frequent night sweats dropped from 33% down to about 12%, essentially matching the general population. So if you also snore loudly, wake up gasping, or feel exhausted despite a full night’s sleep, sleep apnea could be driving both your fatigue and your sweating.
Thyroid Problems and Metabolic Heat
An overactive thyroid speeds up your metabolism, which means your body generates more heat around the clock, including while you sleep. People with hyperthyroidism often notice sensitivity to heat, warm skin, and excessive sweating as early symptoms. The sweating isn’t limited to nighttime, but it can be more noticeable at night because you’re lying still under covers with nowhere for the heat to go.
Other signs that point toward a thyroid issue include unexplained weight loss, a racing heartbeat, anxiety, and trembling hands. A simple blood test can confirm or rule this out quickly.
Infections and Illness
Your body raises its temperature to fight infection, and sweating is how it cools back down. This is why night sweats are common with the flu, COVID, and other viral infections. Bacterial infections, including tuberculosis and endocarditis (an infection of the heart valves), can also cause drenching night sweats that persist for weeks. If your night sweats are new, come with a fever, and started during or after an illness, your immune system is likely the cause, and the sweating should resolve as you recover.
When Night Sweats Signal Something Serious
In rare cases, persistent drenching night sweats are an early symptom of certain cancers, particularly lymphoma. Oncologists refer to a specific cluster called “B symptoms”: drenching night sweats, unexplained weight loss (typically more than 10% of your body weight over six months), and recurring fevers. These sweats tend to be severe enough to require changing your sheets, and they don’t improve with environmental changes.
Other warning signs that can accompany lymphoma-related sweats include painless swelling of lymph nodes in your neck, armpits, or groin, persistent fatigue, shortness of breath, or itchy skin. The presence of multiple symptoms from this list, especially unexplained weight loss combined with drenching sweats, warrants prompt evaluation. A physical exam checking for swollen lymph nodes or an enlarged spleen is usually the first step, followed by bloodwork and potentially a lymph node biopsy if anything looks concerning.
Anxiety, Alcohol, and Other Everyday Triggers
Stress and anxiety activate your fight-or-flight system, which raises your heart rate and triggers sweating. If you tend to go to bed anxious or process stressful events in your sleep, your nervous system may be running hotter than it should overnight. Nightmares and vivid dreams can produce the same physical response.
Alcohol is another common trigger that people overlook. Drinking causes blood vessels near the skin to dilate, which releases heat and prompts sweating. It also disrupts the deeper stages of sleep where your body temperature is supposed to drop the most. Even a couple of drinks in the evening can be enough to wake you up damp a few hours later. Spicy food close to bedtime raises core body temperature through a similar mechanism, though the effect is milder and shorter-lived.
Figuring Out Your Pattern
The most useful thing you can do is track when your night sweats happen and what surrounds them. Note what you ate or drank that evening, what the room temperature was, where you are in your menstrual cycle if applicable, and whether you’re taking any medications. Pay attention to whether the sweating is mild dampness or full sheet-soaking, and whether it comes with other symptoms like fever, weight changes, or fatigue.
Occasional sweating on a warm night after a glass of wine is normal physiology. Drenching sweats multiple times a week that persist regardless of your sleep environment, especially combined with weight loss, fevers, or new lumps, tell a different story. The pattern is what separates a thermostat problem from a medical one.