Night Sweats

The NHS describes night sweats as soaking nightclothes or bedding despite a cool sleeping environment. Regular or unexplained episodes need assessment, especially with weight loss, fever, cough or swollen glands.

First clarify what happened It is normal to sweat when a room, mattress or bedding makes you too warm. The NHS describes night sweats as sweating that soaks nightclothes or bedding despite a cool sleeping environment. People sometimes use the term for milder episodes. A clinician therefore asks how wet the clothes became, how often it happens and whether heat explains it. Adults and children can experience night sweats. The symptom describes what happened during sleep and does not identify the cause. Night sweats are not simply overnight fever Sweat glands are controlled by the autonomic nervous system. Sweating helps release heat, but hormones, medicines, stress and low glucose can also activate sweating. During fever, chills often occur while the thermoregulatory set point rises. Sweating may occur when that set point falls towards normal. This fever mechanism can explain some episodes during infection or inflammation. It does not explain every night sweat, and a fever may never be measured. Common non infectious causes Menopause and perimenopause commonly cause vasomotor symptoms. A hot flush can produce sudden heat or cold across the face, neck and chest, followed by sweating at night. Menopause related night sweats may last several minutes and disturb sleep. They do not indicate infection simply because sweating is heavy. Anxiety can increase autonomic activity and sweating. Hyperhidrosis causes excessive sweating and can sometimes occur during sleep. Some antidepressants, steroids, painkillers and other medicines can contribute. Alcohol, recreational drugs and withdrawal from some substances may also cause sweating. Do not stop a prescribed medicine suddenly. A pharmacist or clinician can review its timing, dose and possible alternatives. Low glucose can cause sweating during sleep Hypoglycaemia means blood glucose is too low. It mainly affects people with diabetes who use insulin or certain diabetes medicines. Sweating can occur with hunger, shaking, palpitations, dizziness or confusion. The person may notice damp bedding, a morning headache or disrupted sleep. If you have diabetes and wake sweaty, check your glucose when possible and follow your agreed hypo plan. Recurrent night time hypos need review by your diabetes team. Call 999 if someone is unconscious or not responding normally because severe hypoglycaemia is suspected. Do not give food or drink to an unconscious person. Other hormone and sweating disorders Hyperthyroidism can cause heat intolerance, excessive sweating, tremor, palpitations and weight loss. These symptoms overlap with anxiety, menopause and other conditions. Blood tests are needed to assess thyroid function. Night sweats alone cannot diagnose an overactive thyroid. Infection remains one possibility Tuberculosis can cause night sweats, a cough lasting more than three weeks, fever, appetite loss and weight loss. Symptoms usually develop gradually. Night sweats alone do not diagnose tuberculosis. Possible exposures, travel, examination, chest imaging and infection tests may all influence assessment. Other infections can also cause sweating during fever or recovery. A normal temperature at one moment does not exclude infection. Night sweats do not diagnose lymphoma Lymphoma is one less common cause of persistent night sweats. Its most common presenting feature is usually an unexplained painless lymph node swelling. Lymphadenopathy means enlarged lymph nodes. Infection commonly causes it, while lymphoma and other conditions are less common possibilities. NICE recommends considering a suspected cancer pathway for adults with unexplained lymphadenopathy or splenomegaly. Night sweats, fever, itching, breathlessness and weight loss increase concern within that pattern. The referral pathway does not mean lymphoma is confirmed. Night sweats without a persistent node or other concerning findings are not proof of cancer. Children and young people with unexplained lymphadenopathy or splenomegaly need prompt assessment. Clinicians use a very urgent specialist pathway when lymphoma is suspected. The associated pattern guides assessment A clinician asks about room temperature, bedding, fever, cough, diarrhoea, weight change and appetite. They also ask about menopause symptoms, medicines, alcohol, drugs and diabetes. Travel, tuberculosis exposure, immune suppression and recent illness can change the differential diagnosis. The timing and frequency of episodes are recorded. The examination may include temperature, pulse, weight, lymph nodes, thyroid, chest and abdomen. The clinician checks for splenomegaly, which means an enlarged spleen. There is no universal night sweat test panel Tests are selected from the person's symptoms, background and examination. A full blood count can show blood cell patterns but cannot diagnose infection or lymphoma alone. CRP is an inflammatory marker. A raised or normal result cannot identify or exclude every cause. Glucose or HbA1c testing may support diabetes assessment. Thyroid tests assess possible hyperthyroidism, while targeted infection tests follow exposure and symptom clues. A chest X ray may be appropriate with a persistent cough, tuberculosis risk or another chest concern. It does not exclude every infection or lymphoma when normal. Tuberculosis assessment can also include sputum, blood, skin or other tests. The selected tests depend on symptoms, exposure and the body area involved. A biopsy removes a small tissue sample for laboratory examination. It may establish the cause of a persistent unexplained lymph node, but not every enlarged node requires one. What may happen after assessment Environmental sweating may improve after changing bedding, clothing or room temperature. Persistent symptoms still need review when those changes do not explain the pattern. Menopause related vasomotor symptoms can be discussed with a GP, nurse or pharmacist. Treatment decisions depend on symptoms, health background and personal preferences. Medicine related sweating may improve after a supervised change. Infection, thyroid disease, hypoglycaemia and lymph node disorders each require cause specific care. When to get help Arrange a GP appointment if night sweats regularly wake you, worry you or soak clothing and bedding. Also arrange review with fever, cough, diarrhoea or unexplained weight loss. See a GP for a cough lasting more than three weeks, night sweats that do not go away or known close tuberculosis exposure. Mention relevant travel or exposure directly. Arrange a GP appointment for swollen glands that enlarge, feel hard or fixed, or have not settled within one week. Night sweats or weight loss make review more important. Contact NHS 111 or request urgent GP help if swollen glands cause difficulty swallowing or breathing. Call 999 for severe breathing difficulty, collapse, confusion or reduced responsiveness. Call 999 or go to A&E if you cough up more than a few spots or streaks of blood. Do the same for blood with breathing difficulty, a fast heartbeat or chest or upper back pain. Contact your diabetes team if you have recurring hypos at night. Call 999 for suspected severe hypoglycaemia when someone is unconscious or not responding normally. This lesson explains how clinicians assess night sweats. It cannot identify an individual cause or replace urgent medical care.

Night sweats are a non specific symptom with several possible mechanisms. The environment, frequency, associated symptoms, medicines and health context determine what assessment is needed.