Night Sweats: Causes in Women and Men, and When to Worry

What counts as night sweats?

Night sweats are episodes of heavy sweating during sleep that soak your nightclothes or sheets, when the room isn’t hot and you aren’t over-covered.¹ Waking a bit sticky on a summer night doesn’t count.

They are a common complaint. Depending on who is asked, between 10 and 60 per cent of people report them, and a review found that most people who report night sweats to their doctor do not have a serious underlying condition.^2,3

Common causes of night sweats

• Menopause and perimenopause. The most common cause in women. Night sweats are hot flushes that happen during sleep, and they can start years before periods stop. See hot flushes and perimenopause^1,5
• Medicines. Some medicines for depression, diabetes, pain and fever, and some hormone treatments, can cause sweating^2,3
• Anxiety and low mood. Mood disorders are among the conditions most often linked with night sweats²
• Reflux. Acid reflux at night is a recognised and often overlooked cause²
• An overactive thyroid, which also tends to cause weight loss, a fast pulse and feeling hot during the day²
• Sleep apnoea. In an Icelandic study, frequent night sweating was three times more common in people with untreated sleep apnoea than in the general population, and it fell to normal levels once the apnoea was treated. See sleep apnoea⁴
• Alcohol, particularly in the evening
• Carrying extra weight²

Night sweats in men

Men get night sweats too. Sleep apnoea, medicines, alcohol, reflux, anxiety and infections are the usual explanations. Low testosterone can cause sweats and flushes, most often in men having hormone treatment for prostate cancer.

Less common but serious causes

These are uncommon, and they almost always come with other symptoms:²

• Infections, such as tuberculosis, HIV and infections of the heart valves or bones
• Some cancers, particularly lymphoma, where sweats tend to come with fever, weight loss and swollen glands
• Low blood sugar overnight in people treated for diabetes

When to worry about night sweats

See a doctor soon if night sweats come with any of these:

• Fever
• Weight loss you can’t explain
• A cough lasting more than three weeks, or coughing up blood
• Lumps or swollen glands in your neck, armpits or groin
• Bone pain, or feeling generally unwell
• Recent travel to, or time living in, a country where tuberculosis is common

Also see a doctor if drenching sweats have continued for more than a few weeks without an obvious reason, or if they are disturbing your sleep.¹

How doctors look for the cause

Most of the answer comes from questions about your periods, medicines, alcohol, snoring, mood and other symptoms, plus an examination. If nothing stands out, guidance for doctors suggests a short list of tests: a blood count, thyroid function, a marker of inflammation, tests for tuberculosis and HIV, and a chest X-ray. More extensive testing is kept for people whose results or symptoms point somewhere specific.²

What helps

Treating the cause is what works. In the meantime:

• Keep the bedroom cool and use a fan
• Wear light cotton nightclothes and use layers of bedding you can throw off
• Avoid alcohol, spicy food and hot drinks in the evening
• Keep a cold drink and a spare top by the bed

For menopausal night sweats, hormone therapy is the most effective treatment, and several non-hormonal prescription options exist.⁶ Cognitive behavioural therapy also helps. In a randomised trial it reduced how often night sweats happened and how much they bothered women.⁷

Menopausal sweats can go on for a long time. In one large study they lasted more than seven years for over half the women who had them, so it is worth asking about treatment instead of waiting them out.⁵

References

1. healthdirect. Night sweats.
2. Bryce C. Persistent Night Sweats: Diagnostic Evaluation. Am Fam Physician. 2020;102(7):427-433.
3. Mold JW, Holtzclaw BJ, McCarthy L. Night sweats: a systematic review of the literature. J Am Board Fam Med. 2012;25(6):878-93.
4. Arnardottir ES, Janson C, Bjornsdottir E, et al. Nocturnal sweating--a common symptom of obstructive sleep apnoea: the Icelandic sleep apnoea cohort. BMJ Open. 2013;3(5).
5. Avis NE, Crawford SL, Greendale G, et al. Duration of menopausal vasomotor symptoms over the menopause transition. JAMA Intern Med. 2015;175(4):531-9.
6. New Collective Author. The 2023 nonhormone therapy position statement of The North American Menopause Society. Menopause. 2023;30(6):573-590.
7. Ayers B, Smith M, Hellier J, et al. Effectiveness of group and self-help cognitive behavior therapy in reducing problematic menopausal hot flushes and night sweats (MENOS 2): a randomized controlled trial. Menopause. 2012;19(7):749-59.