Night sweats are surprisingly common, affecting up to 41% of primary care patients, with the highest rates among people between 41 and 55 years old. Sometimes the cause is as simple as a warm bedroom. Other times, night sweats signal something happening inside your body, from hormone shifts to medications to underlying health conditions. Understanding the most likely causes can help you figure out whether your sweating is routine or worth investigating.
How Your Body Regulates Temperature During Sleep
Your brain has a built-in thermostat located in a region called the preoptic hypothalamus. This area does double duty: it initiates deep sleep and manages your body’s cooling system. When warmth sensors in your skin detect heat, they send signals to this region, which responds by widening blood vessels near the skin’s surface and dialing down internal heat production. This is why your core body temperature starts dropping about two hours before you fall asleep, and why deep sleep tends to begin at the steepest point of that temperature decline.
This cooling process is normal and necessary. Your body creates a warm microclimate under your blankets (the same reason you instinctively curl up or pull covers close), which triggers the skin warmth signals that help you fall into deep sleep. Sweating is part of this cooling mechanism. A light film of moisture overnight is your thermostat working as designed. Night sweats become a problem when you’re waking up with soaked sheets or clothing, or when the sweating disrupts your sleep repeatedly.
A Warm Bedroom Is the Simplest Explanation
Before looking for medical causes, check your sleep environment. Sleep experts recommend keeping your bedroom between 60 and 67°F (15 to 19°C). Anything above 70°F is considered too hot for quality sleep. Heavy blankets, memory foam mattresses that trap heat, and synthetic sleepwear can all push your body past its comfort zone, forcing it to sweat more aggressively to cool down. If your night sweats improve after adjusting these factors, you likely don’t need to look further.
Hormonal Changes and Menopause
Fluctuating levels of estrogen and progesterone are one of the most common causes of night sweats, particularly for women in perimenopause and menopause. These hormones help your brain calibrate its internal thermostat. When their levels rise or fall unpredictably, your brain can misread your actual body temperature, perceive overheating that isn’t really happening, and trigger a sweating response to cool you down. This is the same mechanism behind hot flashes during the day. At night, the result is waking up drenched, sometimes multiple times.
Night sweats from hormonal shifts tend to be most intense during perimenopause (the years leading up to menopause) and can persist for several years afterward. They’re also common during pregnancy, after childbirth, and around menstruation. Low testosterone in men can cause a similar pattern, though it’s less frequently discussed.
Medications That Cause Night Sweats
Antidepressants are among the most well-documented medication triggers. Roughly 10% of people taking SSRIs (a common class of antidepressants) and 5 to 20% of those on SNRIs (another common class) experience excessive sweating as a side effect. A large meta-analysis found that both drug classes roughly triple the risk of excessive sweating compared to a placebo. The sweating can happen day or night, but many people notice it most during sleep because there’s no physical activity to explain it away.
Other medications linked to night sweats include blood pressure drugs, hormone therapies, diabetes medications that lower blood sugar, and over-the-counter fever reducers like acetaminophen and aspirin (which work by resetting your body’s thermostat). If your night sweats started around the same time as a new medication, that timing is worth noting.
Stress, Anxiety, and Nocturnal Panic
Your body’s stress response activates the same nervous system pathways that control sweating. When you’re anxious or under chronic stress, elevated stress hormones can keep your sweat glands more active than usual, including while you sleep. Some people experience nocturnal panic attacks, which are sudden surges of fear and physical symptoms that strike during sleep. These episodes can produce intense sweating, a racing heart, and a feeling of dread, all without any obvious trigger. If you’re going through a particularly stressful period and notice your night sweats worsening, the connection is likely real.
Sleep Apnea and Breathing Disruptions
Obstructive sleep apnea, a condition where the airway repeatedly collapses during sleep, is an underrecognized cause of night sweats. Research from an Icelandic sleep study found a clear link between the severity of sleep apnea and the frequency of nighttime sweating. The connection appears to involve the body’s “fight or flight” nervous system, which activates each time breathing is interrupted. This raises blood pressure and triggers sweating. Notably, both the sweating and the blood pressure elevations improved when patients were treated with a continuous positive airway pressure (CPAP) device.
If your night sweats come with loud snoring, gasping awake, or persistent daytime fatigue, sleep apnea is worth considering. Many people with the condition don’t realize they have it because the breathing interruptions happen while they’re asleep.
Infections and the Immune Response
Infections can cause night sweats through a specific mechanism: your immune system releases inflammatory compounds that temporarily raise the set point of your internal thermostat. This triggers chills and shivering, which drive your core temperature up (a fever). When those inflammatory compounds recede, your thermostat resets to normal, and your body sweats to shed the excess heat. This cycle of fever and sweating tends to follow a pattern tied to the natural rise and fall of immune activity throughout the day, which is why many infections produce sweating that peaks at night.
Short-term infections like the flu or COVID-19 commonly cause a few nights of sweating that resolve on their own. Chronic infections are a different story. Tuberculosis is classically associated with drenching night sweats, and HIV can produce them as well, particularly when the immune system is significantly compromised. These infections cause persistent, recurring sweats rather than a few rough nights during an acute illness.
When Night Sweats May Signal Something Serious
Most night sweats have a benign explanation. But certain patterns and accompanying symptoms warrant a closer look. Drenching sweats that happen every night for two or more weeks call for a more urgent evaluation than intermittent, mild episodes that come and go over months.
Pay attention to whether your night sweats come alongside any of the following:
- Unexplained weight loss
- Persistent or recurring fever
- Swollen lymph nodes in your neck, armpits, or groin
- Easy bruising or unusual bleeding
- New or unexplained rash
This combination of symptoms can point toward conditions like lymphoma, leukemia, or other malignancies. The classic triad in lymphoma is night sweats, unexplained weight loss of more than 10% of body weight, and fever. None of these symptoms alone is cause for alarm, but together they form a pattern that doctors take seriously and investigate promptly.
Practical Steps to Reduce Night Sweats
If you’ve ruled out a medical cause, or while you’re working with your doctor to identify one, environmental and behavioral changes can make a real difference. Keep your bedroom at or below 67°F. Switch to breathable, moisture-wicking sleepwear and bedding made from natural fibers like cotton or linen. Avoid alcohol, spicy food, and caffeine in the hours before bed, as all three can raise your core temperature or interfere with your body’s cooling process.
Layering your bedding so you can easily remove a blanket in the middle of the night gives you more control than using one heavy comforter. Keeping a glass of cold water by the bed helps both with rehydration and with cooling down quickly after an episode. For sweats driven by stress or anxiety, regular physical activity earlier in the day and a consistent wind-down routine before bed can lower baseline stress hormone levels enough to make a noticeable difference.