Night sweats have a wide range of causes, from a bedroom that’s too warm to hormonal shifts, medications, and occasionally serious medical conditions. Your body’s temperature naturally drops during sleep, and sweating is one of the main tools it uses to cool down. When something disrupts that process or forces your body to work harder to regulate heat, you wake up damp or drenched.
How Your Body Regulates Temperature During Sleep
A small region deep in your brain called the preoptic hypothalamus acts as your internal thermostat. It receives temperature signals from your skin, spinal cord, and internal organs, then decides whether to warm you up or cool you down. When this area detects excess warmth, it triggers two responses: it widens blood vessels near the skin’s surface to release heat, and it activates your sweat glands.
During the transition from wakefulness to deep sleep, these same brain circuits actively lower your core body temperature. Specialized neurons in the hypothalamus sense warmth and respond by suppressing the brain’s wake-promoting regions, which is one reason a warm bath before bed can make you drowsy. Your body temperature typically drops by one to two degrees during the night, reaching its lowest point in the early morning hours. If anything interferes with this cooling process, whether it’s a too-warm room, a hormonal imbalance, or a medication side effect, your sweat glands may overcompensate.
Room Temperature and Bedding
The simplest explanation for nighttime sweating is 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. High humidity makes things worse because sweat can’t evaporate efficiently, leaving you feeling overheated even if the air temperature seems reasonable. Heavy blankets, memory foam mattresses that trap heat, and synthetic sleepwear all contribute. Before looking for a medical explanation, it’s worth ruling out these basics.
Hormonal Changes
Hormones play a direct role in how your hypothalamus sets its temperature target. When estrogen and progesterone levels fluctuate, the brain’s thermostat becomes more sensitive, narrowing the range of temperatures your body considers “normal.” Small increases that wouldn’t normally trigger sweating suddenly do.
This is why night sweats are so common during perimenopause and menopause. An estimated 35 to 50 percent of perimenopausal women experience sudden waves of body heat with sweating and flushing that last 5 to 10 minutes. These episodes often strike at night. The exact mechanism isn’t fully understood even after decades of research, but the pattern tracks closely with declining estrogen levels. Night sweats can also occur during pregnancy, the menstrual cycle, and in people with thyroid disorders. An overactive thyroid raises your metabolic rate, generating more internal heat than your cooling system can handle.
Medications That Cause Sweating
Antidepressants are among the most common medication-related causes of night sweats. Roughly 10 percent of people taking SSRIs and 5 to 20 percent of those on SNRIs experience excessive sweating as a side effect. These drugs appear to disrupt the hypothalamus’s thermoregulatory process by affecting serotonin receptors that help control body temperature. Serotonin and dopamine are both critical for the hypothalamus to regulate heat, and altering their levels can essentially miscalibrate the system.
Other medications linked to night sweats include hormone therapy drugs, steroids, blood pressure medications, and some diabetes treatments that can cause low blood sugar overnight. If your night sweats started around the same time as a new medication, that connection is worth discussing with your prescriber.
Alcohol and Diet
Drinking alcohol before bed is a reliable trigger for night sweats. Alcohol increases your heart rate and widens blood vessels in your skin, which pulls heat to the surface and triggers perspiration. It also disrupts sleep architecture, meaning you cycle through sleep stages abnormally, which can further interfere with temperature regulation. You don’t need to drink heavily for this to happen; even a couple of drinks in the evening can be enough.
Spicy foods have a similar effect. Capsaicin, the compound that makes peppers hot, activates the same heat-sensing receptors in your body that respond to actual temperature increases. Eating spicy food close to bedtime can trick your hypothalamus into launching a cooling response you don’t need.
Sleep Apnea
Obstructive sleep apnea, a condition where your airway repeatedly closes during sleep, is an underrecognized cause of night sweats. Each time your airway collapses and your oxygen drops, your sympathetic nervous system fires up in a stress response. This “fight or flight” activation increases heart rate, blood pressure, and sweat gland activity. Many people with untreated sleep apnea report waking up sweaty without realizing the two are connected. If your night sweats come with loud snoring, gasping during sleep, or daytime fatigue, sleep apnea may be the underlying issue.
Infections and Immune Responses
Night sweats are a hallmark symptom of several infections. Tuberculosis classically causes drenching sweats at night alongside a persistent cough, weight loss, fatigue, and fever. HIV can produce night sweats both during acute infection and as the disease progresses. Bacterial infections of the heart valves (endocarditis), bone infections, and deep abscesses also commonly present with nighttime sweating.
The common thread is that your immune system raises your body’s temperature set point to fight infection, creating a fever. When the fever breaks, often during sleep, your body rapidly cools itself through intense sweating. This is why night sweats from infections tend to be more dramatic than those from environmental or hormonal causes.
When Night Sweats Signal Something Serious
Certain types of cancer, particularly lymphomas, produce night sweats as an early symptom. The key distinction is severity: cancer-related night sweats are typically described as “drenching,” meaning your pajamas, sheets, and blankets are soaking wet. This is different from waking up mildly damp or warm.
Lymphoma-related night sweats usually appear alongside other warning signs: painless swollen lumps in the neck, armpit, or groin (enlarged lymph nodes), unexplained weight loss, persistent fatigue, loss of appetite, or an enlarged spleen causing abdominal fullness. These symptoms together are known as “B symptoms” in oncology and prompt further evaluation, typically with blood tests and a lymph node biopsy. Night sweats alone, without these accompanying symptoms, are rarely caused by cancer, but persistent drenching sweats that don’t have an obvious explanation deserve medical attention.
Other Medical Conditions
Several neurological conditions can disrupt the autonomic nerves that control sweating. Autonomic neuropathy, which damages the nerves governing involuntary body functions, can cause unpredictable sweating patterns including night sweats. This is particularly common in people with long-standing diabetes. Rare adrenal gland tumors called pheochromocytomas produce surges of adrenaline that trigger episodes of sweating, rapid heartbeat, and high blood pressure, sometimes during sleep.
Anxiety disorders and chronic stress keep your sympathetic nervous system in a heightened state, which can carry over into sleep. People with PTSD, generalized anxiety, or panic disorder frequently report night sweats, especially during periods of increased stress. The mechanism is the same one behind nervous sweating during the day: your body stays in alert mode and your sweat glands respond accordingly.
Sorting Out the Cause
Occasional night sweats, especially on warm nights or after drinking, are common and rarely concerning. The pattern matters more than any single episode. Keeping a brief log of when sweats happen, what you ate or drank, what medications you’re taking, and what your bedroom conditions were like can help identify a pattern quickly. Night sweats that happen regularly for weeks, soak through your bedding, or come with fever, weight loss, or swollen glands point toward something that needs evaluation beyond adjusting your thermostat.