Cold sweats during sleep happen when your body’s stress response activates while you’re asleep, triggering sudden sweating that isn’t caused by an overheated bedroom or too many blankets. The causes range from harmless (a stressful dream, a warm room) to medically significant (low blood sugar, hormonal shifts, infections, or medication side effects). About 10 to 20% of adults report regular episodes of nighttime sweating, and roughly 30% of people with obstructive sleep apnea experience them.
How Cold Sweats Differ From Ordinary Night Sweats
Ordinary night sweats are your body’s attempt to cool itself down. You overheat, your brain signals your sweat glands, and moisture appears on your skin. Cold sweats work differently. They’re driven by your sympathetic nervous system, the same fight-or-flight wiring that kicks in during a scare or a sudden drop in blood sugar. Your skin feels clammy and cool rather than flushed and hot, because the sweating happens without a rise in core body temperature.
In practice, people use “cold sweats” and “night sweats” interchangeably, and the underlying causes overlap significantly. What matters more than the label is whether the sweating is occasional or persistent, and whether it comes with other symptoms.
Low Blood Sugar While You Sleep
Nocturnal hypoglycemia is one of the most common medical causes of cold sweats at night, especially for people with diabetes. When blood glucose drops below 70 mg/dL during sleep, your body releases adrenaline to raise it back up. That adrenaline surge produces sweating, a rapid heartbeat, and shakiness, often without fully waking you. You might notice damp sheets in the morning or feel unusually tired and groggy, which are clues that your blood sugar dipped overnight.
People who take insulin or certain oral diabetes medications are most at risk. Eating too little before bed, drinking alcohol in the evening, or exercising late in the day can all lower blood sugar enough to trigger an episode. Even people without diabetes can occasionally experience drops in blood sugar after heavy drinking or prolonged fasting.
Hormonal Changes and Menopause
Fluctuating estrogen levels during perimenopause and menopause interfere with the hypothalamus, the part of your brain that acts as your internal thermostat. When estrogen drops, this thermostat essentially becomes oversensitive. It misreads small changes in body temperature and triggers a cooling response: blood vessels near the skin dilate, your face and chest flush, and sweat glands activate. The result is a sudden wave of heat followed by chills and clammy skin.
These episodes can happen multiple times a night and significantly disrupt sleep quality. They typically begin during perimenopause (often in a person’s 40s) and can continue for years. Hormonal changes during pregnancy, menstruation, and thyroid disorders can produce similar nighttime sweating.
Anxiety and Nighttime Panic Attacks
Panic attacks don’t only happen while you’re awake. Nocturnal panic attacks can jolt you out of sleep with sweating, a pounding heart, trembling, shortness of breath, and a feeling of impending doom. The episode typically peaks within minutes and leaves you feeling chilled and clammy afterward.
Even without full panic attacks, chronic anxiety and stress keep your sympathetic nervous system on a higher baseline. This elevated stress tone makes nighttime sweating more likely, particularly during periods of intense worry or after traumatic events. People with PTSD frequently report cold sweats during sleep tied to distressing dreams or fragmented sleep patterns.
Sleep Apnea
Obstructive sleep apnea causes repeated pauses in breathing during sleep. Each pause triggers a brief partial awakening, and these frequent arousals increase sympathetic nervous system activity, which leads to sweating. Research published in the American Journal of Managed Care found that people with sleep apnea were significantly more likely to report night sweats than those without the condition (about 19% versus 12%).
The connection appears to involve oxygen levels. When breathing stops, blood oxygen drops, and the body responds with a stress reaction that includes sweating. If you snore heavily, wake up gasping, or feel exhausted despite a full night of sleep, sleep apnea may be behind your nighttime sweating.
Medications That Cause Nighttime Sweating
Several common medications can trigger sweating during sleep. Unlike primary sweating conditions (which tend to calm down at night), drug-induced sweating often persists or worsens while you’re sleeping. The most frequently implicated categories include:
- Antidepressants: SSRIs, tricyclic antidepressants, and antipsychotics are well-documented causes.
- Pain medications: Opioid painkillers and some anti-inflammatory drugs can trigger nighttime sweating.
- Diabetes medications: Insulin and certain oral medications can cause sweating indirectly by lowering blood sugar.
- Hormone-related medications: Corticosteroids and thyroid medications affect the endocrine system in ways that produce excess sweating.
If your cold sweats started around the same time as a new medication or dosage change, that timing is a strong clue. Nighttime sweating from medications often resolves once the drug is adjusted, but never stop a prescribed medication without talking to the prescribing clinician first.
Infections and Immune Responses
Your immune system ramps up activity at night, which is one reason fevers tend to spike after dark. Acute infections like the flu or COVID-19 commonly produce nighttime sweating that resolves as you recover. More concerning are chronic or serious infections that cause persistent, drenching night sweats over weeks.
The infections most associated with ongoing night sweats include tuberculosis, endocarditis (an infection of the heart’s inner lining), HIV, pneumonia, and mononucleosis. Fungal infections like histoplasmosis, particularly in people who have traveled to regions where these are common, can also present this way. Persistent sweating accompanied by fever, unexplained weight loss, or a cough that won’t clear warrants prompt medical evaluation.
Less Common but Serious Causes
Certain cancers, particularly lymphomas, are known to cause drenching night sweats. In these cases, the sweating is typically severe enough to soak through clothing and bedding, and it occurs alongside other symptoms like unexplained weight loss, persistent fatigue, or swollen lymph nodes. Night sweats alone rarely point to cancer, but when combined with these other signs, they become more clinically significant.
Neurological conditions that affect the autonomic nervous system can also disrupt normal sweat regulation during sleep. And some autoimmune disorders produce inflammatory responses that manifest partly as nighttime sweating.
Patterns Worth Paying Attention To
A single night of cold sweats after a stressful day, a heavy meal, or sleeping in a warm room is rarely a concern. What matters is frequency and context. Sweating that happens most nights for more than two to three weeks, soaks through your clothes or sheets, or wakes you up repeatedly is worth investigating.
Pay attention to what comes with the sweating. Fever and chills point toward infection. Weight loss you can’t explain raises the concern for chronic infection or malignancy. A racing heart and sense of dread suggest panic or anxiety. Snoring and daytime fatigue point toward sleep apnea. Keeping a brief log of when episodes happen, what you ate or drank, and any accompanying symptoms gives your doctor a much clearer picture than a vague description of “sweating at night.”