Doctor Warns of Five Diseases Behind Excessive Night Sweats
A doctor warns that excessive night sweats soaking through clothing can signal serious conditions including hyperthyroidism, low blood sugar, chronic infections, and certain cancers—rather than simple overheating—and should be evaluated if
Dr. Jetsadee Bunyavongvirocha, deputy director of Maha Sarakham Hospital, warns that excessive night sweats soaking through clothing—even without feeling hot—can signal serious underlying conditions and should not be dismissed as simply being hot-natured.
Night sweating is common if caused by a hot room, heavy blankets, late exercise, alcohol, or spicy food before bed. However, persistent drenching sweats that require changing clothes multiple nights in a row—especially when the room is cool and weather is mild—warrant investigation. Excessive night sweats, medically termed hyperhidrosis nocturna, can stem from hormonal changes, medications, low blood sugar, infections, or disease.
Five conditions to watch for include:
1. Hyperthyroidism—the body's metabolism runs in overdrive even while sleeping. Symptoms include feeling unusually hot, easy sweating, heart palpitations, tremors, insomnia, frequent bowel movements, and weight loss despite good appetite. If accompanied by rapid pulse and unexplained weight loss, thyroid hormone testing (TSH and thyroid hormones) should be performed.
2. Low blood sugar at night—particularly in people taking certain diabetes medications. During low blood sugar, the body releases adrenaline to raise glucose levels, causing profuse sweating, heart palpitations, tremors, nightmares, startled awakening, and morning headaches. This occurs more often in insulin users or those on medications that lower blood sugar, especially if eating little at dinner, exercising heavily in the evening, or consuming alcohol. Blood sugar patterns should be reviewed with a doctor rather than self-treating with extra food or medication adjustments.
3. Chronic infections—night sweats combined with fever and weight loss require caution. While tuberculosis is the classic example, many other infections cause this pattern. Warning signs include persistent fever, prolonged cough, unintentional weight loss, loss of appetite, severe fatigue, and enlarged lymph nodes. Anyone coughing for more than two to three weeks with abnormal sputum or blood-tinged phlegm should seek evaluation rather than wait for sweats to resolve on their own.
4. Blood disorders and certain cancers—less common but important not to ignore if other signs are present. Some cancers, particularly lymphomas, can cause excessive night sweats, though symptoms rarely appear in isolation. Other concerning signs include unexplained weight loss, persistent fever, and enlarged lymph nodes or organs.
