Heavy sweating during sleep, often called night sweats, is surprisingly common and usually has a fixable cause. In many cases the culprit is something straightforward: a warm bedroom, thick bedding, or a medication side effect. But persistent, drenching night sweats that soak your sheets can also signal a hormonal shift, a sleep disorder, or occasionally something more serious that deserves medical attention.
Your Bedroom May Be Too Warm
The simplest explanation is often the right one. Your body temperature naturally drops during sleep, and if your environment fights that process, you sweat. Sleep experts at the Cleveland Clinic recommend keeping your bedroom between 60 and 67°F (15 to 19°C). That feels cool to most people when they’re awake, but it’s the range your body needs to cycle through sleep stages without overheating.
Memory foam mattresses, synthetic sheets, and heavy comforters trap heat against your skin. Alcohol before bed widens blood vessels and raises skin temperature, which can trigger sweating hours later even after you’ve fallen asleep. Eating a large or spicy meal close to bedtime has a similar effect because digestion generates heat. If your night sweats happen occasionally and you wake up damp rather than soaked, adjusting these factors often solves the problem entirely.
Hormonal Changes
Hormones are the most common medical cause of night sweats. During perimenopause and menopause, fluctuating estrogen levels disrupt the brain’s internal thermostat. The body misreads its own temperature, triggering a burst of sweating to cool down from heat that isn’t really there. A European survey found that 31 to 52 percent of menopausal women experience moderate to severe hot flashes and night sweats, and these episodes can persist for years.
Men aren’t exempt. Low testosterone (hypogonadism) causes night sweats through a similar mechanism. An overactive thyroid gland also raises your baseline metabolic rate, making your body run hotter around the clock, including during sleep. People with diabetes sometimes sweat heavily at night because their blood sugar drops too low while they’re sleeping, a condition called nocturnal hypoglycemia. This is especially common in people taking insulin or certain oral diabetes medications.
Medications That Cause Night Sweats
If your night sweats started around the same time as a new prescription, the medication itself may be responsible. Antidepressants are the most well-documented offenders. Clinical trials show that 7 to 19 percent of people taking SSRIs (the most commonly prescribed class of antidepressant) develop excessive sweating as a side effect. SNRIs like duloxetine and venlafaxine carry a similar risk.
Other medications linked to night sweats include hormone therapies, steroids, drugs that lower blood sugar, and some over-the-counter fever reducers like aspirin or acetaminophen (which work by resetting your body’s thermostat and can trigger rebound sweating). If you suspect a medication is the cause, don’t stop it on your own. Your doctor can often adjust the dose or switch you to an alternative that doesn’t have this effect.
Sleep Apnea and Night Sweats
About 30 percent of people with obstructive sleep apnea report night sweats, and many don’t realize the two are connected. Sleep apnea causes repeated pauses in breathing throughout the night. Each pause drops your blood oxygen level, and each time your brain jolts you awake (even partially) to resume breathing, your nervous system fires up in a stress response. That stress response raises heart rate and activates sweat glands. The frequent awakenings and accompanying body movements keep your fight-or-flight system running at a higher level than it should during sleep.
If you also snore loudly, wake up with headaches, or feel exhausted despite spending enough hours in bed, sleep apnea is worth investigating. Treating it often resolves the sweating along with the fatigue.
Infections and Immune Conditions
Your immune system generates heat when it fights infection, and that process doesn’t pause at night. Sweating during a cold or flu is normal and temporary. But certain chronic or hidden infections are known for causing persistent night sweats, sometimes as one of the earliest symptoms. Tuberculosis is the classic example, though it’s uncommon in most developed countries. HIV, heart valve infections (endocarditis), and certain types of pneumonia can also produce drenching sweats that persist for weeks.
Some autoimmune conditions trigger the same response. Conditions like sarcoidosis, rheumatoid arthritis, and giant cell arteritis can cause low-grade inflammation that leads to recurring night sweats even without a fever you can measure with a thermometer.
When Night Sweats May Signal Something Serious
Certain cancers, particularly lymphoma and leukemia, list night sweats as a hallmark symptom. Lymphoma-related night sweats are typically severe enough to drench your pajamas and bedding, and they tend to recur over weeks without any obvious trigger. They’re often accompanied by unexplained weight loss, persistent fatigue, or painless swollen lymph nodes in the neck, armpits, or groin.
To be clear, cancer is a rare cause of night sweats compared to everything else on this list. But the combination of drenching sweats plus any of the following should prompt a visit to your doctor sooner rather than later:
- Unintentional weight loss of more than a few pounds over weeks
- Persistent or unexplained fever
- Swollen lymph nodes that don’t go away
- Sweats that persist for weeks without an obvious environmental or hormonal explanation
What Your Doctor Will Check
If you bring up night sweats at an appointment, expect your doctor to start with a detailed history: when the sweating started, how severe it is, what medications you take, and whether you have any other symptoms. This conversation alone often points to the cause. From there, a standard blood panel can check thyroid function, blood sugar levels, inflammatory markers, and signs of infection. If those come back normal and the sweats continue, further workup might include imaging or more specialized testing depending on the pattern of your symptoms.
For most people, the cause turns out to be environmental, hormonal, or medication-related. Keeping a brief log of your night sweats for a week or two before your appointment, including what you ate and drank, your bedroom setup, and how severe the sweating was, gives your doctor a much clearer starting point.
Practical Steps to Reduce Night Sweats
Start with the basics. Set your thermostat to the 60 to 67°F range, switch to breathable cotton or bamboo sheets, and avoid alcohol within three hours of bedtime. Sleeping in lightweight, moisture-wicking clothing (or no clothing) helps your skin release heat naturally. A fan pointed toward the bed creates airflow that accelerates evaporative cooling, which can make a noticeable difference even without changing the room temperature.
If your sweats are hormonally driven, the interventions get more specific. Menopausal night sweats respond well to hormone therapy, and non-hormonal options exist for people who can’t or prefer not to use it. For medication-induced sweating, switching to a different drug in the same class often eliminates the problem. And if sleep apnea is involved, treating it with a CPAP device or oral appliance typically reduces night sweats along with snoring and daytime exhaustion.