Night sweats have a wide range of causes, from hormonal shifts and medications to infections and, less commonly, cancer. Somewhere between 10% and 41% of adults report them, with the highest rates among people aged 41 to 55. Most cases trace back to something treatable or manageable, but persistent drenching sweats, especially alongside other symptoms, deserve medical attention.
Hormonal Changes and Menopause
The single most common cause of night sweats is the drop in estrogen that occurs around menopause. About 75% of perimenopausal and postmenopausal women in the United States experience hot flashes, and when those flashes happen during sleep, you get night sweats. The mechanism involves your body’s internal thermostat. Normally, your brain tolerates a range of core body temperatures before triggering a cooling response. When estrogen declines, that comfortable range narrows dramatically. Even a tiny uptick in core temperature, one you’d never notice otherwise, can trigger a full sweating episode as your body scrambles to cool down.
Interestingly, falling estrogen alone doesn’t fully explain the problem. Elevated activity in the sympathetic nervous system (your “fight or flight” wiring) also plays a role, further shrinking that temperature comfort zone. This is why stress and anxiety can make menopausal night sweats worse. These episodes typically peak in the first few years after periods stop, then gradually ease, though some women deal with them for a decade or longer.
Menopause isn’t the only hormonal trigger. Hyperthyroidism (an overactive thyroid) speeds up your metabolism and raises body temperature around the clock, including at night. Low testosterone in men can produce night sweats through a similar thermoregulatory disruption. And conditions that cause sudden blood sugar drops, like poorly controlled diabetes treated with insulin, can provoke sweating episodes overnight.
Medications
If your night sweats started around the same time as a new prescription, the medication itself may be the cause. Antidepressants are among the most common culprits. As many as 20% of patients taking them experience excessive sweating, and this can be especially noticeable at night. Among antidepressants, certain types are more likely to cause it than others: venlafaxine (an SNRI) and bupropion carry higher risk, while some others are less likely to trigger sweating.
Other drug classes known to cause night sweats include:
- Hormone-blocking therapies used in breast and prostate cancer treatment, which create an artificial menopause-like state
- Fever-reducing medications like aspirin and acetaminophen, which work partly by promoting sweating
- Steroids such as prednisone
- Diabetes medications that can cause overnight blood sugar drops
If you suspect a medication is behind your night sweats, it’s worth discussing alternatives or dosage adjustments rather than stopping on your own.
Infections
Night sweats are a hallmark of several infections, particularly those that produce fevers your body tries to break while you sleep. Tuberculosis is the classic example: drenching night sweats are so closely associated with TB that doctors still consider it early in their evaluation. HIV, especially when undiagnosed or untreated, can cause persistent night sweats. Bacterial infections of the heart valves (endocarditis) and bone infections (osteomyelitis) also produce them. Even common infections like the flu or a lingering sinus infection can cause temporary night sweats that resolve once the illness clears.
Cancer
This is the cause most people fear when they search for answers, and it’s important to put it in context: cancer is one of the least common explanations for night sweats. That said, it’s the reason doctors take persistent, unexplained night sweats seriously.
Lymphoma, a cancer of the immune system, is the malignancy most strongly linked to night sweats. The sweats associated with lymphoma tend to be drenching, the kind that soak your sheets and pajamas enough to require changing them. They typically don’t appear alone. Other warning signs include painless swelling of lymph nodes in your neck, armpits, or groin, unexplained weight loss (usually defined as losing more than 10% of body weight over six months without trying), persistent fatigue, fevers, and chills. Leukemia and certain hormone-producing tumors can also cause night sweats.
The key distinction: cancer-related night sweats are persistent, worsening over weeks, and accompanied by other symptoms. If your night sweats come and go, or you can link them to something obvious like a warm bedroom or a spicy dinner, cancer is very unlikely.
Sleep Apnea
Obstructive sleep apnea, where your airway repeatedly collapses during sleep, is an underrecognized cause of night sweats. When your airway closes, oxygen levels drop and your body mounts a stress response to jolt you awake enough to start breathing again. That stress response activates your sympathetic nervous system, which triggers sweating. People with sleep apnea often don’t realize they’re waking up dozens of times per night, so they notice the sweating without understanding the cause.
If your night sweats come with loud snoring, morning headaches, daytime exhaustion, or a partner who notices you stop breathing in your sleep, sleep apnea is worth investigating. Treating it often resolves the sweating.
Anxiety and Stress
Your nervous system doesn’t fully shut off during sleep. If you’re dealing with chronic stress, anxiety, or post-traumatic stress, your sympathetic nervous system can remain on high alert overnight, producing sweating episodes that feel a lot like hormonal night sweats. Panic attacks can also happen during sleep, waking you up with a racing heart and drenched skin. These episodes are uncomfortable but not dangerous, and they typically improve when the underlying anxiety is addressed.
Everyday Causes Worth Ruling Out
Before assuming something medical is going on, it’s worth checking the basics. A bedroom that’s too warm, heavy bedding, or synthetic pajamas that trap heat are the most common reasons people wake up sweating. Alcohol, even a glass or two of wine, causes blood vessels to dilate and can produce noticeable sweating a few hours into sleep as your body metabolizes it. Spicy food close to bedtime raises core body temperature. Intense exercise in the evening can keep your metabolic rate elevated for hours.
These situational causes tend to be obvious once you think about them, and they resolve when you change the habit. Medical night sweats, by contrast, happen regardless of your sleep environment.
Patterns That Matter
Only about 12% of patients who experience night sweats actually report them to their doctor, which means most people either assume they’re normal or don’t think they’re worth mentioning. In many cases, that’s fine. But certain patterns signal something worth investigating: night sweats that persist for more than two or three weeks without an obvious cause, sweats severe enough to soak through your bedding, and sweats accompanied by fever, weight loss, new lumps, persistent fatigue, or pain. A doctor’s evaluation typically starts with a thorough medication review, blood work to check thyroid function, blood sugar, inflammatory markers, and infection indicators, and a physical exam focusing on lymph nodes. Imaging is usually only needed if the initial workup points toward something specific.