Your body is supposed to get warmer at the skin surface when you sleep. About two hours before you fall asleep, your core temperature begins dropping under the control of your internal clock, and it continues falling by roughly 1°C (about 1.8°F) through the night. To shed that internal heat, your body pushes warm blood toward your skin, which is why your hands, feet, and trunk can feel noticeably hot under the covers. But if you’re waking up drenched in sweat or feeling uncomfortably overheated, something beyond normal biology may be going on.
How Your Body Regulates Temperature During Sleep
Your brain operates on a 24-hour temperature cycle. Core body temperature peaks in the late afternoon and starts declining in the evening, reaching its lowest point in the early morning hours. The likelihood of falling into deep sleep is highest when this rate of decline is steepest. By climbing under a blanket, you create a skin microclimate of about 33 to 35°C (91 to 95°F), which is 2 to 3°C warmer than during waking hours. That warmth at the surface is actually part of the cooling process: dilated blood vessels near the skin release heat from your core outward.
This system works well when everything is in balance. Problems start when something interferes with your body’s ability to cool down, whether that’s your bedroom environment, something you ate or drank, a hormonal shift, or a medication.
Your Bedroom May Be Too Warm
The simplest and most common explanation is that your sleeping environment is working against your body’s natural cooling. Sleep experts at the Cleveland Clinic recommend keeping your bedroom between 60 and 67°F (15 to 19°C). That range supports the stability of REM sleep and gives your body enough of a temperature gradient to release heat efficiently. If your room is 72°F or warmer, or if you’re using heavy bedding, your body can’t offload heat fast enough and you’ll feel it.
Memory foam mattresses, synthetic sheets, and thick comforters all trap heat close to your skin. Switching to breathable fabrics and lighter layers can make a noticeable difference without changing anything else.
Alcohol and Spicy Food Before Bed
Drinking alcohol in the evening causes blood vessels to widen, which initially makes you feel warm and flushed. That vasodilation leads to rapid heat loss through the skin, triggering a stress response as your body scrambles to compensate. The result is a spike in adrenaline and cortisol that can wake you up feeling hot and sweaty hours after your last drink, even if you felt fine going to sleep.
Spicy food has a similar effect. In one study, young healthy men who ate hot sauce with dinner had elevated body temperature during the first sleep cycle. Capsaicin, the compound that makes peppers hot, interferes with temperature regulation through two pathways: it triggers the release of chemicals that widen blood vessels near the skin, and it alters metabolic heat production. The men in the study took longer to fall asleep and spent less time in deep, restorative sleep stages. If you regularly eat spicy meals close to bedtime, this alone could explain what you’re experiencing.
Hormonal Changes and Menopause
For women in perimenopause or menopause, nighttime overheating often comes down to hot flashes. Declining estrogen levels narrow what’s called the thermoneutral zone, the range of core body temperatures your brain considers “normal.” In premenopausal women, this zone is wide enough that small temperature fluctuations don’t trigger a response. After menopause, the zone shrinks so dramatically that even a tiny rise in core temperature, fractions of a degree, can set off the brain’s emergency cooling system: sudden sweating, flushed skin, and a wave of intense internal heat.
Hot flashes affect the vast majority of women going through natural or surgical menopause. They’re driven by heightened activity in the sympathetic nervous system, the same “fight or flight” wiring that responds to stress. Estrogen therapy effectively eliminates hot flashes in most women by raising the temperature threshold at which sweating kicks in, essentially widening that thermoneutral zone back to its previous range.
Thyroid Problems
An overactive thyroid gland (hyperthyroidism) speeds up your metabolism, and one of the most recognizable symptoms is increased sensitivity to heat. Thyroid hormones influence every cell in the body, controlling how fast you burn fats and carbohydrates and how much heat your body generates at rest. When these hormones are overproduced, your baseline heat output rises. You may notice that you feel warm not just at night but throughout the day, along with other signs like unexplained weight loss, a rapid heartbeat, or anxiety.
Low Blood Sugar at Night
If you take insulin or certain diabetes medications, nighttime overheating could signal a drop in blood sugar while you sleep. When glucose levels fall too low, your body releases adrenaline as part of a fight-or-flight response. That adrenaline surge causes sweating, a pounding heart, tingling, and anxiety. Some people wake up drenched without realizing their blood sugar dipped. If you have diabetes and regularly wake up hot and sweaty, checking your blood sugar levels overnight (or using a continuous glucose monitor) can help identify whether this is the cause.
Medications That Cause Night Sweats
Several common medications can make you overheat at night, and antidepressants are among the most frequent culprits. In one primary care study, people taking SSRIs (a widely prescribed class of antidepressants) were about three times more likely to report night sweats than those not taking them. Roughly 9% of all patients in the study experienced night sweats, and the mechanism appears to involve changes in noradrenaline, a chemical messenger that influences both mood and temperature regulation. Other medications linked to nighttime sweating include blood pressure drugs, hormone therapies, and some pain relievers. If your symptoms started around the same time as a new prescription, that connection is worth exploring with your prescriber.
When Nighttime Heat Is Worth Investigating
Feeling warm under the covers is normal. Sweating so heavily that you need to change your sheets or nightclothes is not. Pay attention to whether your nighttime overheating is new, whether it’s getting worse, and whether it comes with other changes. Fever, unintentional weight loss, decreased appetite, swollen lymph nodes, or a new rash alongside night sweats are red flags that point toward something your doctor should evaluate. Even without those additional symptoms, night sweats that happen regularly and disrupt your sleep are worth bringing up at your next appointment.