Night sweats, also referred to as nocturnal hyperhidrosis (Hyperhidrosis - a medical term for excessive sweating + nocturnal - night), is the repeated occurrence of excessive sweating during sleep. The person may or may not also perspire excessively while awake. One of the most common causes of night sweats in women over 40 is the hormonal changes related to menopause and perimenopause. This is a very common occurrence during the menopausal transition years. Over 80% of women experience hot flashes, which may include excessive sweating, during menopause. Night sweats range from being relatively harmless to a sign of underlying disease. Night sweats may happen because the sleep environment is too warm, either because the bedroom is unusually hot or because there are too many covers on the bed. Night sweats have been associated with a long list of clinical conditions. However, there is very little evidence that supports clinical recommendations for this condition. Associated conditions The condition may be a sign of various disease states, including but not exclusive to the following: Cancers Lymphoma Leukemia Infections HIV/AIDS Tuberculosis Mycobacterium avium-intracellulare infection Infectious mononucleosis Fungal infections (histoplasmosis, coccidioidomycosis) Lung abscess Infective endocarditis Brucellosis Pneumocystis pneumonia (most often - in immunocompromised individuals) Omicron variant of COVID-19 Endocrine disorders Premature ovarian failure Hyperthyroidism Diabetes mellitus (nocturnal hypoglycemia) Endocrine tumors (pheochromocytoma, carcinoid) Orchiectomy Rheumatic disorders Takayasu's arteritis Temporal arteritis Other Obstructive sleep apnea Gastroesophageal reflux disease Chronic fatigue syndrome Fibromyalgia Granulomatous disease Chronic eosinophilic pneumonia Lymphoid hyperplasia Diabetes insipidus Prinzmetal's angina Anxiety Pregnancy Menopause Drugs Antipyretics (salicylates, acetaminophen) Antihypertensives Anabolic–androgenic steroids, in particular trenbolone, and the nandrolones Dinitrophenol - a common side effect Phenothiazines Drug withdrawal: ethanol, benzodiazepines, cannabis, heroin (and other opioids), Over-bundling Autonomic over-activity Inflammatory bowel disease (IBD) - Crohn's disease/ulcerative colitis References External links Sleep disorders Medical signs Menopause