Night sweats, also known as nocturnal hyperhidrosis, is the repeated occurrence of excessive sweating during sleep. The person may or may not also perspire excessively while awake. Night sweats range from being relatively harmless to a sign of underlying disease. Some of the most common causes of night sweats include hormonal changes related to menopause and perimenopause, which is a very common occurrence during the menopausal transition years. Night sweats can also be caused by medication such as antidepressants, hormone therapy, and drugs used to treat low blood sugar with diabetes. Other causes of night sweats include anxiety disorders, autoimmune disorders, sleep disorders such as sleep apnea, tuberculosis, and alcohol use disorder. Night sweats can be a symptom of COVID-19. Depending on the cause of your night sweats, there are some tips that may help you feel more comfortable and cooler during the night, such as wearing loose-fitting pajamas made of natural fibers, using lightweight bedding, using a fan or air conditioning in your bedroom, and sipping cold water through the night. If you have night sweats regularly that wake you up or worry you, you should see a GP to check if you have any other symptoms.