Night Sweats in Men: Causes and When to See a Doctor

What Counts as True Night Sweats?

Feeling slightly sweaty in bed does not necessarily mean you are experiencing true night sweats.

A warm room, heavy bedding, thick sleepwear, recent exercise or alcohol can make anyone perspire during sleep. True night sweats continue despite correcting these environmental factors.

Doctors may ask whether the sweating wakes you or requires you to change your clothes or bedding. This helps establish its severity but cannot identify the cause on its own.

What Causes Night Sweats in Men?

The causes of night sweats in men range from environmental heat and medication effects to hormone changes, sleep disorders and infections.

Two particularly relevant male causes are low testosterone and androgen deprivation therapy for prostate cancer. Men are also more likely than women to develop obstructive sleep apnea.

Low Testosterone

Low testosterone, also called male hypogonadism, is a possible cause of hot flashes and night sweats in men.

When testosterone levels become abnormally low, some men experience sudden warmth, flushing and sweating without a fever.

Testosterone-related night sweats rarely occur alone. Other possible symptoms include:

• Reduced sex drive
• Erectile dysfunction
• Persistent fatigue
• Loss of muscle strength
• Increased body fat
• Low mood
• Difficulty concentrating
• Reduced facial or body hair
• Fewer spontaneous erections

A low laboratory result alone is not enough to diagnose hypogonadism. The Endocrine Society’s testosterone guideline recommends making the diagnosis only when a man has compatible symptoms and consistently low testosterone levels.

Testing normally involves measuring testosterone early in the morning and repeating the test on another day. Additional tests may be needed to determine why the level is low.

Testosterone treatment is not appropriate for every man with a low result. A healthcare professional should confirm the diagnosis, investigate the cause and discuss the possible benefits and risks.

Prostate Cancer Treatment

Prostate cancer itself does not commonly cause isolated night sweats. However, night sweats and hot flashes are frequent effects of androgen deprivation therapy.

Androgen deprivation therapy, or ADT, lowers testosterone to slow prostate cancer growth. This hormone reduction can affect temperature regulation and produce:

• Hot flashes
• Facial or upper-body flushing
• Night sweats
• Chills after sweating
• Sleep disruption

Other effects may include fatigue, reduced libido, erectile dysfunction, loss of muscle mass, weight gain, mood changes and gradual bone loss.

The American Cancer Society lists hot flashes among the common side effects of prostate cancer hormone therapy.

Tell your cancer-care team if these symptoms are frequent or interfere with sleep. ADT should not be stopped or changed without medical guidance.

Obstructive Sleep Apnea

Obstructive sleep apnea causes repeated pauses in breathing when the upper airway closes during sleep. These episodes may activate the body’s stress response and contribute to nighttime sweating.

Sleep apnea is more common in men. Risk also increases with age, obesity, a larger neck circumference, alcohol use and certain anatomical features.

Symptoms that may point to obstructive sleep apnea include:

• Frequent loud snoring
• Witnessed pauses in breathing
• Choking or gasping during sleep
• Repeated awakenings
• Dry mouth in the morning
• Daytime sleepiness
• Difficulty concentrating
• Reduced libido

The National Heart, Lung, and Blood Institute confirms that sleep apnea is more common in men and may require a sleep study for diagnosis.

Night sweats alone do not prove that sleep apnea is present. They become more suggestive when combined with snoring, gasping and daytime sleepiness.

Medications

Night sweats sometimes begin after starting a medication, increasing its dose or changing how it is taken.

Medications associated with excessive sweating include:

• Some antidepressants
• Corticosteroids
• Thyroid hormone
• Insulin and other medicines that can lower blood sugar
• Opioid pain medicines
• Testosterone-lowering treatments
• Certain blood pressure medicines

Medication-related sweating usually occurs without fever. The timing of symptom onset is often the most useful clue.

Do not stop a prescribed medication suddenly. Some medicines must be reduced gradually, and stopping them may create additional health risks.

Low Blood Sugar During Sleep

Men with diabetes who use insulin or certain diabetes medicines may experience low blood sugar while sleeping. This is called nocturnal hypoglycemia.

The body releases stress hormones when glucose drops too low. These hormones can cause heavy sweating, trembling and a rapid heartbeat.

Possible signs include:

• Damp pajamas or sheets
• Nightmares
• Restless sleep
• Morning headache
• Fatigue or irritability after waking
• Confusion
• An unexpectedly high or low morning glucose result

The National Institute of Diabetes and Digestive and Kidney Diseases identifies sweating and nightmares as possible signs of low blood glucose during sleep.

A glucose meter or continuous glucose monitor can help determine whether sweating occurs during a glucose drop. Severe hypoglycemia causing a seizure, loss of consciousness or inability to swallow safely is an emergency.

Hyperthyroidism

Hyperthyroidism occurs when the thyroid gland produces too much thyroid hormone. This increases metabolism and heat production, which may cause sweating during both the day and night.

Other warning signs of thyroid problems may include:

• Heat intolerance
• Rapid or irregular heartbeat
• Trembling hands
• Anxiety or nervousness
• Unexplained weight loss
• Frequent bowel movements
• Muscle weakness
• Difficulty sleeping

The American Thyroid Association lists increased sweating, heat intolerance, weight loss and a rapid or irregular heartbeat among the possible symptoms.

A blood test measuring thyroid-stimulating hormone and thyroid hormones can help confirm or exclude an overactive thyroid.

Infections

Infections can cause sweating when a fever rises or begins to fall. Night sweats related to infection are more concerning when they occur with a documented fever.

Possible infections include:

• Influenza or another viral illness
• Pneumonia
• Tuberculosis
• HIV
• Infective endocarditis
• Mononucleosis

Other symptoms may include:

• Fever or chills
• Persistent cough
• Fatigue
• Reduced appetite
• Shortness of breath
• Swollen lymph nodes
• Unexplained weight loss

Travel history, immune status, occupation and recent exposures help determine which infections should be considered.

Anxiety and Stress

Anxiety, panic attacks, nightmares and intense emotional stress can activate the fight-or-flight response during sleep. This response increases heart rate and stimulates sweat glands.

Stress may be contributing when night sweats occur during periods of emotional strain and are accompanied by:

• Racing thoughts
• Palpitations
• Nightmares
• Sudden awakenings
• Muscle tension
• Daytime anxiety

Anxiety should not automatically be blamed for persistent sweating. Medications, sleep problems, hormone changes and other medical causes may still need to be considered.

Alcohol and Substance Withdrawal

Alcohol can interfere with sleep and affect the nervous system. Heavy drinking may contribute to nighttime sweating, while alcohol withdrawal can cause sweating, shaking, nausea, anxiety and a rapid heartbeat.

Withdrawal from alcohol or certain drugs can become dangerous. Severe shaking, confusion, hallucinations or seizures require emergency care.

Other Less Common Causes

Less common causes include autoimmune disease, neurological conditions affecting the autonomic nervous system and rare hormone-producing tumors.

Gastroesophageal reflux disease has also been associated with night sweats, but evidence for a direct connection is limited. Reflux is more plausible when sweating occurs with heartburn, regurgitation or nighttime chest discomfort.

Doctors usually investigate common causes and follow clues from the medical history before testing for rare conditions.

Can Night Sweats in Men Be a Sign of Cancer?

Yes, but cancer is an uncommon cause of night sweats, particularly when sweating is the only symptom.

The cancers most commonly associated with drenching night sweats are lymphoma and leukemia. Cancer-related night sweats are more likely to occur with:

• Unexplained weight loss
• Persistent or recurring fever
• Enlarged lymph nodes
• Easy bruising or bleeding
• Pale skin
• Recurrent infections
• Persistent fatigue
• Reduced appetite

Night sweats, fever and weight loss are known as systemic or “B” symptoms in lymphoma. However, night sweats alone cannot diagnose lymphoma or confirm that cancer is present.

A painless lymph node that remains enlarged, grows or appears with systemic symptoms should be examined.

When Should Men See a Doctor?

Arrange a medical appointment if night sweats:

• Occur regularly despite keeping the bedroom cool
• Repeatedly soak your pajamas or bedding
• Wake you or interfere with sleep
• Have no clear environmental explanation
• Began after starting or changing a medication
• Occur with symptoms of low testosterone
• Occur with loud snoring or pauses in breathing
• May be related to low blood sugar
• Are persistent or becoming more severe

Contact a healthcare professional promptly if night sweats occur with:

• Persistent or recurring fever
• Unexplained weight loss
• Enlarged lymph nodes
• Persistent cough
• Recurrent infections
• Severe or worsening fatigue
• Unusual bruising or bleeding
• Reduced appetite
• Symptoms following possible tuberculosis exposure

Seek urgent medical care for:

• Chest pain
• Severe shortness of breath
• Fainting
• New severe confusion
• A seizure
• Suspected severe hypoglycemia
• Severe alcohol or drug withdrawal symptoms

These warning signs do not necessarily indicate cancer, but they require timely assessment.

How Do Doctors Diagnose Persistent Night Sweats?

There is no single test that identifies every cause of night sweats. Evaluation begins with the medical history and physical examination.

A healthcare professional may ask about:

• When the sweating began
• How frequently it occurs
• Whether it soaks clothing or bedding
• Bedroom temperature and sleepwear
• Fever, cough or recent illness
• Weight changes
• Snoring and pauses in breathing
• Diabetes and glucose results
• Reduced libido or erectile dysfunction
• New medications or dose changes
• Alcohol and drug use
• Recent travel
• Tuberculosis or HIV exposure
• Prostate cancer treatment

The examination may include checking temperature, heart rate, thyroid gland, lymph nodes, heart, lungs and abdomen.