What causes night sweats?

They are different from simply feeling warm in bed: clothing or bedding may become damp enough that you need to change them. A single episode can have an ordinary explanation, while repeated drenching episodes deserve attention.

A hot room, heavy bedding, alcohol, spicy food, stress or a fever can trigger sweating during sleep. Hormonal shifts, including those around menopause, can cause hot flushes and sweating. Some medicines can also alter sweating or temperature regulation.

Infections may bring fever, chills, tiredness or swollen glands alongside night sweats. Tuberculosis, brucellosis, glandular fever and HIV infection can present with night sweats. An overactive thyroid can make heat intolerance, tremor, palpitations or unintended weight change more noticeable. Less commonly, blood cancers such as Hodgkin lymphoma or chronic myeloid leukaemia can include night sweats among their symptoms.

Keep the bedroom cool, use lighter layers and note whether episodes follow particular food, drinks, medicines or illnesses. Record when they happen, whether they wake you, and any fever, pain, cough, weight change, rash or enlarged glands.

Do not stop prescribed medicine on your own. If sweating began after a new medicine or dose change, ask the prescriber or pharmacist whether it could be contributing. If hot flushes are affecting sleep, a clinician can discuss options, including whether hormone replacement therapy is suitable for you.

Arrange a medical appointment for persistent or recurrent drenching night sweats, especially if they interrupt sleep or have no clear environmental trigger. Bring your symptom record and a list of medicines, supplements and recent travel or animal exposures.

Seek urgent assessment if night sweats occur with trouble breathing, chest pain, confusion, fainting, coughing blood, a severe headache with a stiff neck, or if you feel seriously unwell. These symptoms need prompt evaluation regardless of the cause of sweating.

Ask what details in your history could point to a cause, whether your medicines may be relevant, and which examination or tests would help clarify the problem. Tell the clinician about fever, cough, diarrhoea, pain, menstrual changes, recent infections, travel, close contacts and changes in weight or appetite.