What causes night sweats in women?

Menopause is the leading cause in women in their 40s and 50s: night sweats are hot flashes that happen in sleep, and hot flashes are usually worst in the first 1 to 2 years. Medicines, anxiety, alcohol, an overactive thyroid and a warm bedroom affect women as well. Night sweats can also start before periods stop, during perimenopause.

What causes night sweats in men?

In men the common causes are a warm room, alcohol, medicines such as antidepressants and steroids, anxiety, reflux, obesity and sleep apnea. An overactive thyroid and, rarely, infection or lymphoma are the medical causes clinicians check.

When should I worry about night sweats?

See a doctor soon if night sweats come with weight loss you can't explain, a fever, swollen glands lasting more than four to six weeks, a cough lasting 3 weeks or more, or easy bruising. Get emergency care for fever with a stiff neck, confusion or a severe headache. The NHS also suggests seeing a GP if night sweats regularly wake you up or worry you.

Are night sweats a sign of cancer?

Rarely. Drenching night sweats are one of the signs of lymphoma, usually alongside painless swollen glands in the neck, armpit or groin, fever with no known reason, or weight loss with no known reason. Night sweats on their own are much more often linked with menopause, medicines, anxiety or reflux.

What blood tests check for the cause of night sweats?

When history and examination don't explain them, the American Family Physician review suggests a complete blood count, C-reactive protein (CRP, an inflammation marker), TSH for the thyroid, an HIV test, a TB test and a chest X-ray. A blood sugar check is added for people with diabetes or episodes that suggest low blood sugar.

Can anxiety cause night sweats?

Yes. The NHS lists anxiety as a cause, and the American Family Physician review links mood disorders, panic disorder and post-traumatic stress disorder (PTSD) with night sweats.

Can low blood sugar cause night sweats?

Yes, mainly in people taking insulin or diabetes pills such as sulfonylureas. NIDDK lists “sweating enough to make your pajamas or sheets damp,” nightmares, and waking tired, irritable or confused as signs of low blood sugar during sleep.

What causes night sweats? The common reasons in men and women

Q: What causes night sweats?

The most common causes are a warm room or bedding, alcohol, menopause, medicines (some antidepressants, steroids and painkillers), anxiety, reflux, obesity, sleep apnea and an overactive thyroid. Low blood sugar at night can cause them in people taking insulin or some diabetes pills. Infections such as TB and HIV and cancers such as lymphoma are much rarer causes.

Quick answer

Night sweats are sweating at night heavy enough to soak your nightclothes or sheets when the room is not too hot; they are common, reported by up to 41% of primary care patients, and on their own are not linked with a higher risk of death. ¹² The usual causes are a warm room or bedding, alcohol, menopause, medicines such as antidepressants and steroids, anxiety, reflux, sleep apnea and an overactive thyroid; low blood sugar at night matters for people on insulin or some diabetes pills. ¹²⁵ When the history does not explain them, clinicians commonly check a blood count, CRP, TSH, an HIV test, a TB test and a chest X-ray. ¹ Night sweats with unexplained weight loss, fevers, swollen glands or a cough lasting 3 weeks or more need a doctor soon, and fever with a stiff neck or confusion needs emergency care. ¹⁶⁹

The distinctions

01
Sweating because the room is hot is not night sweats
Waking damp under a heavy duvet in a warm room is the body cooling itself. Night sweats mean soaking your nightclothes or sheets when the room is not too hot, and only that kind is worth investigating.
02
The company night sweats keep matters more than the sweats
Night sweats on their own are common and, in primary care, are not linked with a higher risk of death. Night sweats with weight loss you can't explain, fevers, swollen glands or a lasting cough are a different picture and need a doctor soon.

Night sweats are sweating at night heavy enough to soak your nightclothes or bedding when the room is not too hot, and most have an everyday cause: a warm room or heavy bedding, alcohol, menopause, a medicine such as an antidepressant or steroid, or anxiety. ¹² Reflux, sleep apnea (breathing that stops and starts in sleep), excess weight and an overactive thyroid are the common medical causes, and low blood sugar at night matters for people on insulin or some diabetes pills. ¹⁵ Infections such as tuberculosis (TB) and HIV, and cancers such as lymphoma, are rare causes that usually bring other signs with them. ¹⁸

When to get help now

Most night sweats are not dangerous. These signs are the exceptions.

Call 911 or your local emergency number

Fever with a stiff neck, a severe headache or confusion ⁹
Very high fever with drowsiness, a new rash or difficulty staying awake
Passing out, a seizure or not waking properly in someone on insulin or diabetes pills; give nothing by mouth to someone not fully awake ⁵

See a doctor soon, the same day if you can

Weight loss you can't explain, more than about 5% of your weight over 6 to 12 months ¹
Fevers, chills or feeling shivery along with the sweats ²
Swollen glands in the neck, armpit or groin, especially lasting more than four to six weeks ¹⁸
A cough lasting 3 weeks or more, chest pain or coughing up blood ⁶
Easy bruising or bleeding, or tiredness that keeps getting worse ¹
Recent travel, a possible HIV exposure, or contact with someone with TB ¹⁷

LifeFrom can't examine you or assess a symptom. If something feels seriously wrong, trust that and get care rather than waiting on a test.

What counts as night sweats?

The NHS defines night sweats as sweating “so much that your night clothes and bedding are soaking wet,” and notes that sweating at night is normal if the room or bedding is too warm. ² Clinicians also use a stricter definition from research: “sweating at night even when it is not excessively hot in your bedroom.” ¹ That second line is the one to hold on to. Feeling damp under a winter duvet is the body cooling itself; changing a soaked T-shirt in a cool room, night after night, is the symptom worth a look.

Night sweats are common. A 2020 review in American Family Physician puts the share of primary care patients who report them at up to 41%, and notes that “The presence of night sweats alone does not indicate an increased risk of death.” ¹ What a clinician weighs is the company they keep: fever, weight loss and swollen glands are the signs that make a serious cause more likely. ¹

Up to 41%of primary care patients report night sweatsPersistent night sweats on their own were not linked with a higher risk of death. Source: American Family Physician, 2020. ¹

What can cause it, most likely first

Ranked from most to least likely in adults in general. The order shifts with age, sex and history: menopause tops the list for women in their 40s and 50s, a new medicine for anyone who started one recently, and infections for people with travel, exposure or a weak immune system.

01
A warm room, heavy bedding or warm nightclothesEverydaycommon
The NHS says sweating at night is normal if the room or bedding makes you too hot. ² A heated bedroom, a thick duvet, synthetic sheets, a partner or a pet sharing the bed all add heat. If the sweats stop when the room is cool, there is no symptom to investigate.
02
Alcohol and drug useEverydaycommon
Alcohol is one of the causes the NHS lists, along with drug use. ² The American Family Physician review lists alcohol and tobacco use among the associated causes too. ¹ Sweats that come on the nights you drink, or when cutting back after heavy drinking, point here.
03
Menopause and perimenopauseMedicalcommon
Night sweats are among the most common symptoms of menopause, which usually arrives between 45 and 55, and hot flashes are usually worst in the first 1 to 2 years. ³ The American Family Physician review names menopause as one of the conditions most often linked with night sweats. ¹ Menopause is usually recognized from age and periods; hormone tests can support it. ³
FSH
A high FSH (follicle stimulating hormone) fits menopause; in perimenopause it swings month to month, so a provider may repeat it if periods have not stopped. ³
Estradiol
A low estradiol with a high FSH fits menopause; one result while periods continue says little. ³
04
MedicinesEverydaycommon
Medicines linked with night sweats include SSRI antidepressants, steroids, thyroid hormone, painkillers and insulin or diabetes pills that lower blood sugar. ¹² The NHS lists “sweating more than normal” among the common side effects of antidepressants, and sweating can also come with coming off them. ¹¹ A start date that lines up with the sweats is a strong clue. Do not stop a medicine on your own; a prescriber can weigh the options.
05
Anxiety, panic and post-traumatic stressMedicalcommon
The NHS lists anxiety as a cause, and the American Family Physician review links mood disorders, panic disorder and PTSD with night sweats. ¹² Racing thoughts, nightmares or waking with a pounding heart alongside the sweats point this way. No blood test checks it; a conversation with a clinician does. If low mood comes with thoughts of harming yourself, call or text 988.
06
Reflux, sleep apnea and excess weightMedicalcommon
Gastroesophageal reflux disease (GERD, stomach acid rising into the gullet) and obesity are among the conditions most often linked with night sweats, and sleep apnea is on the list too. ¹ Loud snoring, gasping, morning headaches and daytime sleepiness point to sleep apnea, which no blood test checks; a sleep study does. See can't sleep for more on what disturbs sleep.
07
Overactive thyroidMedicalless common
An overactive thyroid (hyperthyroidism) speeds up the body, with “sweating or trouble tolerating heat,” weight loss despite a bigger appetite, trouble sleeping and nervousness. ⁴ It is one of the conditions most often linked with night sweats, and TSH is part of the standard first tests. ¹
Can be linked with Hyperthyroidism
TSH
A low TSH (thyroid stimulating hormone) points to an overactive thyroid; it is the first test. ¹ High-dose biotin can make TSH look falsely low. ¹⁰
Free T4
A high free T4 with a low TSH fits an overactive thyroid. ¹⁰ See how to read your thyroid panel.
08
Low blood sugar at nightMedicalless common
In people taking insulin or diabetes pills such as sulfonylureas, blood sugar can drop overnight. ⁵ NIDDK lists “sweating enough to make your pajamas or sheets damp,” nightmares or crying out, and waking tired, irritable or confused as signs. ⁵ For many people with diabetes, low means a reading below 70 mg/dL. ⁵ A home glucose meter or continuous glucose monitor catches night-time lows; a daytime blood test usually does not. Very low blood sugar can cause passing out or a seizure, and someone on these medicines who cannot be woken properly needs 911. ⁵
HbA1c
HbA1c reads average blood sugar over recent months, so it can look normal or on target while lows happen at night; it is useful context, not a test for night-time lows. See blood sugar explained.
09
Infections: TB, HIV and othersMedicalrare
Tuberculosis brings sweating at night with a cough lasting 3 weeks or longer, chest pain, weight loss, fever and chills. ⁶ Early HIV infection can cause fever, chills, rash and night sweats about two to four weeks after infection. ⁷ Endocarditis (infection of the heart valves) and mononucleosis are other infections on the list, and malaria and fungal infections after travel. ¹ TB is checked with a skin test or a blood test (an interferon-gamma release assay) and a chest X-ray. ¹ Night sweats with a cough lasting 3 weeks or more, fevers or weight loss you can't explain need a doctor soon. ¹⁶
HIV antigen/antibody test
A positive result points to HIV infection and is confirmed with further tests; a negative result helps rule HIV out, though a test taken within a few weeks of an exposure can miss a very new infection, so it may be repeated. It is part of the first round for unexplained night sweats. ¹ See viral tests explained.
CRP
A high CRP (C-reactive protein) points to inflammation or infection somewhere in the body; it does not say where. ¹ See inflammation markers explained.
White blood cell count
A high white count can point to infection; an unusually high or low count, or abnormal cells, is followed up. ¹
10
Lymphoma and other cancersMedicalrare
Drenching night sweats are one of the signs of Hodgkin lymphoma, together with painless swollen glands in the neck, armpit or groin, fever with no known reason and weight loss with no known reason in the past 6 months. ⁸ The American Family Physician review notes that fever, drenching night sweats and weight loss mean a worse outlook in lymphoma, which is why that combination is never ignored. ¹ Night sweats alone are rarely the first sign, but night sweats with swollen glands, fevers or weight loss you can't explain need a doctor soon. ¹⁸
White blood cell count
Part of the complete blood count; a white count that is unusually high or low, or abnormal cells on the smear, is a reason to look further. ⁸ See the CBC explainer.
LDH
A high LDH (lactate dehydrogenase) “may be a sign of tissue damage, lymphoma, or other diseases”; it is not specific. ⁸
ESR
A high sedimentation rate (ESR) “may be a sign of lymphoma or another condition”; like CRP it flags inflammation without naming a cause. ⁸

These are things a symptom like this can be linked with, not a diagnosis. Several can sit together, and a clinician who knows your history puts them in order for you.

Night sweats in women

For women in their 40s and 50s, the commonest answer is menopause. Night sweats are hot flashes that happen in sleep, and MedlinePlus lists them among the common symptoms, with hot flashes “usually worst during the first 1 to 2 years.” ³ Periods can turn irregular for one to three years before they stop, and sweats often begin in that window. ³ Waking soaked several times a night is also a direct route to tiredness and brain fog, so if those are part of it, see fatigue and brain fog. Women get the other causes too, so new sweats with a racing heart and weight loss point toward the thyroid rather than menopause. ⁴

Night sweats in men

Men search for this almost as often as women, and the causes are mostly the same minus menopause: a warm room, alcohol, medicines such as antidepressants and steroids, anxiety, reflux, obesity and sleep apnea. ¹² Heavy snoring with night sweats and daytime sleepiness is a common combination in men worth raising, because sleep apnea is treatable and needs a sleep study, not a blood test. ¹ For a man with no weight loss, fever or swollen glands, the serious causes are uncommon. ¹

Why do I sweat only at night?

Several of the causes cluster at night by their nature. Night sweats are the night-time version of the hot flashes of menopause, which wake people from sleep. ³ Sleep apnea happens only in sleep, and reflux is linked with night sweats too. ¹ Low blood sugar from diabetes medicines can strike during sleep, with damp sheets and nightmares as the clues. ⁵ And infections such as TB list “sweating at night” among their signs. ⁶ Daytime sweating as well as night sweats can point to a general cause such as hyperhidrosis (a harmless tendency to sweat heavily) or an overactive thyroid. ²⁴

What tests check for the cause of night sweats?

Most people need no tests: the history (room, alcohol, medicines, periods, mood, snoring) explains it. When it does not, the 2020 American Family Physician review lays out a short first round: a complete blood count, C-reactive protein, TSH, an HIV test, a TB test and a chest X-ray. ¹ Blood sugar is checked when diabetes or low blood sugar is in the picture. ¹ Patients who complete that basic workup and are unlikely to have a serious cause are usually reassured and watched over time rather than sent for more tests. ¹

Test	What it looks for	When it is added
Complete blood count (WBC and others)	Infection, blood cancers, anemia	First round ¹
CRP or ESR	Inflammation or infection somewhere in the body	First round (CRP) ¹
TSH, then free T4	Overactive thyroid	First round ¹
HIV antigen/antibody	HIV infection	First round ¹
TB skin or blood test, chest X-ray	Tuberculosis, lung problems	First round ¹
FSH, estradiol	Menopause	Women with changing periods ³
Glucose, HbA1c, home meter	Low or high blood sugar	People with diabetes or episodes of shakiness ¹⁵
LDH	Tissue damage, sometimes lymphoma	When lymphoma is a concern ⁸
Sleep study	Sleep apnea	Snoring, gasping, daytime sleepiness ¹

The panel that checks these

If a clinician tests, a blood count, CRP and TSH come first, with HIV and TB tests, because together they rule out the treatable medical causes. ¹ None needs fasting except a fasting glucose. FSH and estradiol are for women with changing periods, and LDH and ESR come in when lymphoma is a concern.

FSHMenopause and perimenopause
EstradiolMenopause and perimenopause
TSHOveractive thyroid
Free T4Overactive thyroid
HbA1cLow blood sugar at night
HIV antigen/antibody testInfections: TB, HIV and others
CRPInfections: TB, HIV and others
White blood cell countInfections: TB, HIV and others · Lymphoma and other cancers
LDHLymphoma and other cancers
ESRLymphoma and other cancers

Already have results?Add them to LifeFrom and it reads these markers side by side, against each other and over time, in plain language. Free, on the web or in the app.

Add your results Download the app

LifeFrom doesn't sell blood tests. It reads results from any lab and helps you prepare for your own doctor; it doesn't diagnose.

Getting a useful test

Keep a two-week log: which nights, how soaked, room temperature, alcohol, late meals, medicines, and any fever you measured.
Weigh yourself and note the date; weight loss over months is one of the signs clinicians look for. ¹
List every medicine with its start date, including antidepressants, steroids, thyroid hormone and diabetes medicines. ¹
Mention high-dose biotin, which can make TSH look falsely low; the American Thyroid Association advises stopping it for at least 2 days before thyroid testing, a step to agree with your clinician. ¹⁰
Mention travel, possible HIV exposure and any contact with TB. ¹
One result is a snapshot; see why trends beat single readings.

What may help

Most night sweats ease when the trigger is found. These everyday steps help whatever the cause, and none replaces checking the red flags above.

Start with the everyday things

Keep the bedroom cool, and use lighter, breathable bedding and nightclothes. ²
Cut back on alcohol, especially in the evening. ²
If reflux wakes you, raise it with a clinician; it is one of the conditions most linked with night sweats. ¹
Keep a glass of water and a spare T-shirt by the bed to get back to sleep faster.
If anxiety is part of it, talking therapy and regular wind-down routines help; see can't sleep.

No supplement is listed here, because none has good evidence for night sweats and the causes worth finding need a clinician. Supplements support general wellness. They don't treat the causes above, and if a test finds one, treating that comes first. If you take medicines, are pregnant or have a health condition, check with your clinician before starting anything.

Questions to ask your clinician

Could any of my medicines explain the sweats?
Could this be perimenopause or menopause, and what are the options if it is?
Do I need a blood count, CRP, TSH, HIV or TB test, or a chest X-ray?
Should I have a sleep study for snoring or sleep apnea?
Which signs would mean I should come back sooner?

This page is general education, not medical advice or a diagnosis. Night sweats have many causes that can overlap, and the clinician who knows your history and examines you is the one to read your results and put them in order.

Free in LifeFromAdd the lab results you already have, and LifeFrom reads each marker next to the others it moves with, in plain language, with the sources it used. Free, on the web or in the app.

Start on the web Download the app

Citations

Educational context only, not medical advice or a diagnosis. Always discuss your results with a clinician.

What causes night sweats? The common reasons in men and women, and the tests that check them