Why do I sweat so much that my hair is wet at night?

Night sweats are episodes of heavy sweating during sleep, even when the bedroom and bedding are comfortable. A damp pillow or soaked sleepwear can help describe the severity to a clinician. Alcohol, spicy food, stress, fever, and some medicines may increase sweating. Menopause can cause night-time hot flushes, while an overactive thyroid may bring heat intolerance, tremor, weight change, or a fast heartbeat.

Infections such as glandular fever or brucellosis can cause sweating alongside fever and tiredness. Persistent sweats can also occur with conditions affecting the blood or lymph system, including lymphoma or chronic myeloid leukaemia, but sweating alone cannot identify the cause. HIV infection is another possible cause in the right clinical context.

Keep the room cool, choose breathable sleepwear, and use lighter bedding for several nights. Record when the sweating happens, whether it soaks clothes or bedding, and any fever, cough, pain, weight change, palpitations, or medication changes. Review the timing of alcohol, spicy meals, exercise, and stressful events. Do not stop a prescribed medicine without medical advice.

Arrange a GP appointment if the episodes keep returning, disturb sleep, or have no clear environmental explanation. The clinician may ask about your health history, examine you, and decide whether tests are needed.

Seek urgent medical help for heavy sweating with chest pain, severe breathlessness, fainting, confusion, a severe headache, or signs of a serious allergic reaction. Arrange prompt assessment if sweating comes with a persistent fever, unexplained weight loss, swollen glands, a persistent cough, or marked weakness. These symptoms need assessment because the combination matters, not because night sweating by itself confirms a particular illness.

Ask: Could a medicine, hormonal change, infection, or thyroid problem explain this? What details should I track before my appointment? Which symptoms would mean I need urgent care? Would an examination or blood tests help clarify the cause?