Dr. Rae Osborn 23 May 2022

Night sweats are when a person experiences unusual perspiration at night to the point that bedding and clothes need to be changed. It is important to understand that there are many reasons why excessive night-time perspiration occurs. Not all causes are pathological and some are due to a normal change in life.

How sweating occurs

Sweating (hidrosis) in normal conditions occurs to cool the body. A signal sent to the sweat glands in the skin causes the release of sweat, which cools the body to prevent overheating.

The nervous system plays a crucial role in the process of sweating. Details on the process of sweating are described below:

  • Sensory receptors called thermoreceptors detect temperature changes and send signals to the hypothalamus in the brain.
  • The hypothalamus then sends signals down the spinal cord to the peripheral nerves.
  • These nerves activate the sweat glands to release the sweat.
  • There is a feedback mechanism in which sweat production is halted once the hypothalamus detects that body temperature is in the normal range.

While perspiration is a normal response to hot temperatures due to weather or exercise, it can be a result of other internal factors. Sweating at night can mean that there is some disease or infection but it can be due to normal hormonal fluctuations or medication. Many factors can impact the hypothalamus causing sweating to occur.

The causes of night sweats

While perspiration is a normal response to hot temperatures due to the weather or exercise, it can be a result of other internal factors. Sweating at night can mean that there is some disease or infection in place but it can sometimes also be due to normal hormonal fluctuations or medication. Many factors can impact the hypothalamus causing sweating to occur.

There are many causes of night sweats (nocturnal hyperhidrosis) including infections caused by bacteria, fungi, or viruses. Metabolic and hormonal changes can cause hyperhidrosis during sleep as can cancer and vascular disease.

Sometimes nocturnal sweating is due to normal changes in the body, such as menopause. The use of medication, alcohol and illegal drugs can also result in excessive sweating during sleep.


Menopause often occurs at about age 50 in women, and it is when hormone levels drop. Estrogen production, in particular, decreases. This change in estrogen has an impact on other hormones in the body, causing night sweats. Menopause is a normal part of a woman’s life and represents a time when ovulation stops and progesterone levels also drop.


Infections caused by pathogenic bacteria, fungi, and viruses can cause nocturnal sweating. This happens when the infection causes fever and the body starts to sweat in order to cool down. Examples of such infections include:

  • Tuberculosis: This is a lung infection caused by a bacterium, Mycobacterium tuberculosis.
  • Brucellosis: A bacterial illness due to Brucella bacteria.
  • Covid-19: An infection due to coronavirus.
  • Influenza: A viral infection causing flu.
  • HIV: This is a virus that can lead to AIDs.
  • Histoplasmosis: This infection is due to Histoplasma fungal spores that are inhaled.
  • Coccidioidomycosis: Also known as San Joaquin Valley fever, this fungus occurs in the soils of the southwestern U.S.
  • Lung abscess: A sore inside the lungs that is due to infection by fungi or bacteria.
  • Endocarditis: This is when heart valves become infected and inflamed due to bacteria that have spread from elsewhere in the body.
  • Osteomyelitis: Sometimes an infection can occur in the bones due usually to Staphylococcus bacteria.


Malignant cancers can result in excess sweating at night because the body is trying to fight the illness or because hormone levels have changed. Examples of cancers known to cause this are listed below:

  • Leukemia: This is cancer that happens to the bone marrow.
  • Lymphoma: This is a cancerous condition of the lymphatic system.
  • Ovarian cancer: Malignant ovarian tumors can develop.
  • Carcinoid tumors: Slow-growing cancerous tumors.

Endocrine, reproductive, and vascular problems

Alterations in hormone levels are not always normal and can be due to illness. Hormones released by the endocrine and reproductive systems are important for the normal functioning of the body. Changes associated with these hormones can cause hyperhidrosis at night.

These conditions are all listed below.

  • Hyperthyroidism: This is when the thyroid glands release excessive levels of thyroxine.
  • Hemochromatosis: Excess iron is deposited in the organs.
  • Diabetes mellitus: A condition in which blood sugar is not properly regulated due to either a problem with the pancreas or cells not responding to the hormone insulin.
  • Diabetes insipidus: This is when body fluids are not properly balanced.
  • Hypoglycemia: Low blood sugar can result in night sweats. While this can be due to diabetes, some people with the condition do not have diabetes.
  • Phaeochromocytoma: A benign tumor that develops in the adrenal gland.
  • Orchiectomy: This is when one or both testes are removed, which sometimes is required to treat testicular cancer.
  • Takayasu's arteritis: This is when blood vessels become inflamed. It is an uncommon illness that often results in night sweats.

Medications, drugs, and alcohol

Night sweats can be a side effect of medications including chemotherapy drugs, steroids, and antidepressant medicines. Besides prescribed medication, alcohol and illegal drug use can also cause excess perspiration during sleep.

Diagnosis of night sweats

Night sweats can only be treated if the underlying cause is diagnosed. Diagnosis can be made by physical examination and various tests. Blood tests can be done to check hormone levels or to look for cancer markers. Imaging tests and biopsies can be done if cancer is suspected.

Treatment of night sweats

Once the reason for night perspiration is determined, a proper course of treatment can begin. Some treatment options are given below.

  • Menopausal women having hot flashes and sweats can take hormone replacement therapy.
  • Bacterial infections can be treated with antibiotics.
  • Antivirals may help with viral illnesses.
  • Cancer can be treated with chemotherapy, radiation, or surgery.
  • Medication can treat metabolic and hormone problems.


Night sweats can sometimes indicate that a person has a disease that needs to be treated. It is essential that a doctor determines the cause of a person’s night sweats so that proper treatment can begin if the condition is due to a disease process or infection.

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About the Author:

Dr. Rae Osborn has a Ph.D. in Biology from the University of Texas at Arlington. She was a tenured Associate Professor of Biology at Northwestern State University where she taught many courses for Pre-nursing and Pre-medical students. She has written extensively on medical conditions and healthy lifestyle topics, including nutrition. She is from South Africa but lived and taught in the United States for 18 years.


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