Feeling cold and sweating at the same time during the night happens when your brain’s internal thermostat misfires, triggering heat-loss responses (sweating) that then leave you chilled. This contradictory sensation is surprisingly common, and while it’s often caused by something manageable like your sleep environment, medications, or hormonal shifts, it can occasionally signal an underlying condition worth investigating.
Why Your Body Sweats and Feels Cold Simultaneously
Your brain has a built-in thermostat located in a region called the preoptic area of the hypothalamus. This area maintains a “thermoneutral zone,” a narrow temperature window where your body doesn’t need to heat up or cool down. When everything works normally, minor fluctuations in your core body temperature stay within that window and go unnoticed.
The cold-and-sweaty paradox happens when that thermoneutral zone narrows. A tiny, normally insignificant rise in core temperature gets misread as overheating, so your brain launches a full cooling response: blood vessels near the skin dilate and sweat glands activate. The sweating then rapidly drops your body temperature below the comfortable range, leaving you shivering under damp sheets. Your body isn’t actually overheating. It’s a miscommunication in temperature signaling that triggers an exaggerated reaction, followed by the chill that comes from all that heat loss.
This cycle can repeat multiple times in a single night, disrupting deep sleep and leaving you exhausted in the morning.
Hormonal Changes
Menopause is the most recognized hormonal trigger. Declining estrogen levels destabilize the thermoneutral zone, making it so narrow that even a fraction of a degree change in core temperature sets off drenching perspiration followed by chills. These episodes, called vasomotor symptoms, affect the majority of people going through perimenopause and can persist for years.
Low testosterone in men (hypogonadism) produces a similar effect, as does an overactive thyroid. Hyperthyroidism revs up your metabolism, generating excess internal heat that your body then overcorrects for with sweating. Pregnancy and the postpartum period also shift hormonal balance enough to cause nighttime sweating and chills.
Low Blood Sugar During Sleep
If you manage diabetes with insulin, overnight drops in blood sugar (nocturnal hypoglycemia) are a common culprit. When blood glucose falls too low, your body releases stress hormones to compensate. Those hormones activate your sweat glands, and you may wake up with damp sheets and clothing, feeling cold and confused. Some people sleep through these episodes entirely and only notice the damp bedding and fatigue the next morning.
Medications That Cause Night Sweats
Antidepressants are one of the most common medication-related causes. About 22% of people taking antidepressants report night sweats as a side effect, with certain drugs in the SSRI and SNRI classes being particularly likely offenders. Hormone replacement therapy can also trigger nighttime sweating, which is ironic given that it’s often prescribed to treat menopausal symptoms. If your cold-and-sweaty nights started around the same time as a new medication, that timing is worth noting.
Sleep Apnea
Obstructive sleep apnea has a strong, often overlooked connection to night sweats. In a study of over 800 newly diagnosed sleep apnea patients, 31% reported frequent nighttime sweating (three or more times per week), compared to just 11% of the general population. The repeated breathing interruptions stress your body and disrupt normal temperature regulation.
The good news: when patients in that study used a CPAP machine consistently, their sweating rates dropped from 33% to about 12%, essentially returning to normal population levels. If you snore heavily, wake up gasping, or feel exhausted despite a full night’s sleep, sleep apnea could be driving both the sweating and the chills.
Infections and Immune Responses
Your immune system uses fever as a weapon against infection, and the sweating-then-chills cycle is a byproduct of that process. Common infections like the flu, mononucleosis, and pneumonia all produce night sweats. The pattern is familiar: your temperature spikes, you sweat to cool down, and then you feel freezing.
Tuberculosis is classically associated with night sweats, typically alongside a persistent cough lasting three weeks or more, unintentional weight loss, fatigue, and loss of appetite. HIV, endocarditis (an infection of the heart valves), and other chronic infections can also present with recurring night sweats as an early or ongoing symptom.
Anxiety and Mental Health Conditions
Anxiety disorders, panic disorder, depression, and PTSD are all recognized causes of night sweats. Stress hormones activate the same fight-or-flight pathways that trigger sweating during the day, and these responses don’t shut off at bedtime. If you’re waking up cold and sweaty and you’re also dealing with persistent worry, intrusive thoughts, or disrupted mood, the connection may not be coincidental.
Less Common but Serious Causes
Night sweats are listed among the “B symptoms” of lymphoma and leukemia, where they typically appear alongside unexplained weight loss (more than 10% of body weight over six months), persistent fevers, and extreme fatigue. Autoimmune conditions like rheumatoid arthritis and sarcoidosis can produce night sweats as well, as can rarer endocrine tumors.
These causes are far less likely than the ones above, but they’re the reason persistent, unexplained night sweats deserve a medical evaluation, especially when paired with weight loss, swollen lymph nodes, or fevers that won’t resolve.
Your Sleep Environment Matters
Before investigating medical causes, check the basics. Cleveland Clinic sleep experts recommend keeping your bedroom between 60 and 67°F (15 to 19°C). Anything above 70°F is too warm for quality sleep and can trigger sweating that then leaves you chilled once your blankets are kicked off. High humidity compounds the problem by making it harder for sweat to evaporate, trapping moisture against your skin.
Breathable, moisture-wicking bedding and lighter layers you can adjust during the night help break the sweat-then-chill cycle for people whose symptoms are environmentally driven.
What a Medical Workup Looks Like
If your symptoms are persistent, happening multiple times a week, or accompanied by other changes like weight loss or fatigue, a doctor will typically start with blood work. The standard panel includes a complete blood count (to check for infection or blood cancers), inflammatory markers, thyroid function tests, blood glucose, and screening for viral infections like HIV and Epstein-Barr virus. From there, further testing depends on what the initial results suggest and what other symptoms you’re experiencing.
Keeping a brief log of your episodes, including how often they happen, how severe the sweating is, and whether you notice other symptoms, gives your doctor a much clearer starting point than a vague description of “it happens sometimes.”