Doctors often hear their patients complain of night sweats. Night sweats refer to excess sweating during the night. While night sweats are often due to a sleeping environment that is too warm (e.g. if your bedroom is unusually hot or you are wearing too many bedclothes), they can also be caused by an underlying medical condition. True night sweats are severe hot flashes occurring at night that can drench your clothes and sheets and that are not related to an overheated environment.

It is important to note that flushing (a warmth and redness of the face or body) may be hard to distinguish from true night sweats. If you are one of the many people who suffer from night sweats, classified as excessive sweating at night, then you may be wondering about the potential causes and if you should be concerned.

If your night sweats occur on a regular basis, interrupt your sleep, or are accompanied by a fever or other symptoms, such as unexplained weight loss, then you should schedule an appointment with your physician. There are many different causes of night sweats. To find the cause, a doctor must get a detailed medical history and order tests, such as blood counts and virus and thyroid tests, to decide what medical condition is responsible for the night sweats. Some of the known conditions that can cause night sweats are:


Known as “hot flashes” during the day, night sweats are very common for women going through menopause and are often the first sign. The hot flashes that accompany menopause can occur at night and cause sweating. This is a very common cause of night sweats in women.


Bacterial infections like endocarditis (inflammation of the heart valves), osteomyelitis (inflammation within the bones) and abscesses may result in night sweats. Tuberculosis is the infection most commonly associated with night sweats. Night sweats are also a symptom of HIV infection.

Chronic Sweating

Hyperhidrosis (Idiopathic) is a medical condition in which the body chronically produces too much sweat without any identifiable environmental or medical cause. There are two types. Primary hyperhidrosis is idiopathic, bilaterally symmetric, excessive sweating of the axillae, palms, soles, face, and, less commonly, scalp or inguinal folds. Secondary hyperhidrosis may be focal or generalized, and is caused by an underlying medical condition or medication use.


Night sweats can be early indicators of some cancers. The most common type of cancer associated with night sweats is lymphoma. However, a person with an undiagnosed cancer typically experiences additional symptoms, such as unexplained weight loss and fever.


Since hypoglycemia, or low blood sugar, can cause sweating, people who are taking medications to lower blood sugar, like insulin and oral anti-diabetics, may experience sweating at night.

Hormone disorders

Night sweats can be a result of problems in hormone-producing glands (the endocrine system). Sweating or flushing can be seen with several hormone disorders, including pheochromocytoma, carcinoid syndrome, and hyperthyroidism. If a person receives too much or too little of a hormone, such as serotonin, it can result in flushing and sweating. Night sweats may also be a side effect of hormone therapy medications that regulate the amount of hormones in your system.


Stress and emotional problems that cause sweating during the day can often have the same effect at night. Anxiety can lead to night sweats because the body’s stress response has been activated (along with changes in metabolism, heart rate, body temperature etc). Particularly if a person experiences nightmares, it’s normal to have a physiological response to that fear.


Taking certain medications can lead to night sweats. Antidepressant medications are a common type of drug that can lead to night sweats. Other psychiatric drugs have also been associated with night sweats. Medicines taken to lower fever, such as aspirin and acetaminophen, can sometimes lead to sweating. Many other drugs can cause night sweats or flushing.

Neurologic Conditions

Uncommonly, neurologic conditions including autonomic dysreflexia, posttraumatic syringomyelia, stroke, and autonomic neuropathy may cause increased sweating and may lead to night sweats.

Practical reasons (non-medical conditions) for why someone may experience night sweats include:

Spicy foods or hot drinks before bedtime

Hot weather or an over-heated bedroom

Excessive amounts of blankets or bedclothes

Exercising before bedtime

Before visiting your doctor, try to eliminate the practical causes of night sweats from your daily routine and sleeping environment. Keep your bedroom at a comfortable temperature for sleeping, avoid using extra blankets on your bed, and stop exercising or eating spicy foods late in the evening. If your night sweats persist, then make an appointment with your family physician.