Skin problems health centre

Why do I sweat at night?

Just as during the day, sweating at night may be simply due to being too hot, whether because of warm weather, an over-heated bedroom or excessive bedclothes.

However, excessive night-time sweating, known medically as nocturnal hyperhydrosis, typically causes someone to wake at night with their nightclothes or sheets drenched in sweat, even when the room temperature is cool. This may be a symptom of a medical condition, so if the problem persists, seek medical advice.

Possible causes of night sweats include:

• The hormonal changes of menopause
• Infections, including tuberculosis, abscesses, HIV/AIDS, osteomyelitis (infection of bone) and endocarditis (affecting the heart)
• Anxiety
• Medications, including antidepressants, aspirin, prednisolone, drugs to lower blood sugar and hormone treatments
• Sleep apnoea, a condition in which breathing repeatedly pauses during sleep, often associated with snoring
• Alcohol or drug misuse, especially of heroin
• Low blood sugar in diabetes
• Hormonal disorders including hyperthyroidism (an overactive thyroid gland)
• Gastro-oesophageal reflux disease ( GORD), where acid from the stomach flows back up the oesophagus (gullet)
• Stroke and some neurological conditions
• Lymphoma, leukaemia or some cancers. This is a rare cause of night sweats and is usually accompanied by other symptoms such as unexplained weight loss.

If you experience repeated night sweats that wake you up or are accompanied by other symptoms such as fever or weight loss, seek medical advice. Your GP may perform various tests to look for any underlying problem. Sometimes no cause can be identified despite investigation.