Night sweats are a specific type of sweating that, like the name implies, only occur at night. True night sweats are caused by severe hot flashes that occur in sleep. They often cause a person to soak through bed sheets and are not related to how hot the surrounding environment is. Night sweats are also surprisingly common.[1] One study published in the Annals of Family Medicine found that 41% of patients questioned about night sweats at a primary care clinic responded that they had experienced night sweats in the month prior to their visit to the doctor. This is only one statistic and is not representative of the number of people in society as a whole who experience night sweats, but it still demonstrates that night sweating is a prevalent issue.[2] There are various medical reasons that people experience night sweats ranging from benign to quite serious. Below is a list of several of the most common causes.

Hyperhidrosis

Hyperhidrosis is the medical term used to describe unusual, excessive sweating that is not related to the heat or exertion. The two most common types of hyperhidrosis are called primary focal hyperhidrosis and secondary generalized hyperhidrosis. Most commonly, night sweats are a symptom of secondary hyperhidrosis - which is a type of hyperhidrosis caused by an underlying medical condition or medication. For example, some medications cause excessive sweating as a side effect. Due to the fact that the excessive sweating has a causative agent, the medication, a person would be said to have secondary hyperhidrosis. In contrast, primary focal hyperhidrosis develops earlier on in life and has no causative factor.[3] While primary focal hyperhidrosis could potentially cause night sweats, this is much less common.[1] The other causes of night sweats discussed in this article are actually types of secondary generalized hyperhidrosis.

Pregnancy and Menopause

Sometimes, normal physiological changes that occur over a lifetime can be the cause of night sweats.[1] This is especially true for women. Both pregnancy and menopause can night sweats due to the hormonal changes they cause in the body. Menopause typically begins some time during a woman’s 40’s or 50’s and signals the fact that her body is at the end of its childbearing years. Between 30% and 80% of women experience hot flashes and/or night sweats during and after menopause. However, it is always a good idea to have a doctor determine whether menopause is truly occuring to make sure that hot flashes are not being caused by a different, more sinister, underlying cause. This can easily be determined through a simple blood test.[4]

Hormonal Imbalances

Several hormonal disorders are known to cause both flushing, sweating, and night sweats. The causes and complications of these disorders vary and there is a wide array of possible endocrine diseases that can cause night sweats. Here are a few:

  • Pheochromocytoma
  • Carcinoid syndrome
  • Hyperthyroidism
  • Diabetes and Hypoglycemia[1][5]
  • This is not an exhaustive list of endocrine disorders that can lead to night sweats so be sure to check in with a medical professional if you are concerned that an endocrine problem may be causing your sweating issues.

    Infection

    There are several infections that can lead to the development of night sweats. Some of these include:

  • Tuberculosis
  • Bacterial infections (like endocarditis or osteomyelitis)
  • HIV
  • Influenza
  • Other febrile illnesses
  • It should also be noted that a fever in and of itself can cause night sweats to occur as the body struggles to fight off an infection. If you suspect that an infection is causing your night sweats then it is imperative that you speak with your doctor.[1][5]

    Cancer

    Unfortunately, sometimes night sweats are an early symptom of certain types of cancer. Lymphoma is the cancer most commonly associated with night sweats.[1] Leukemia can also cause night sweats.[5] If you are suffering from cancer you will most likely have other health issues that go along with your night sweats like weight loss and fevers. If you are experiencing night sweats along with other troubling health symptoms please speak with a doctor.[1]

    Mental Health Issues

    Another common cause of night sweats are mental illnesses. Most commonly anxiety is associated with night sweating, but it can also be caused by depression. For those who struggle with substance abuse disorders the drug of abuse as well as withdrawal from it can cause night sweats.[5]

    Sleep Issues

    Sleep disorders are associated with the development of night sweats.[2] This is especially true in the case of people who have obstructive sleep apnea. People with this sleep disorder are reportedly three times more likely to experience night sweats than the general population.[5] It is unknown whether other types of sleep disorders, like restless leg syndrome, are themselves responsible for night sweats or whether other factors are causing the night sweats and people with sleep issues are just more likely to notice them. More studies need to be done in order to determine the relationship between sleep disorders and night sweating.[2]

    Medications

    Medication side effects are one of the leading causes of night sweats. In fact, many commonly prescribed medicines cause secondary generalized hyperhidrosis as well. Here is a list of some of the medications that can cause night sweats:

  • Pain medications: many types of opiates, NSAIDs (which are over the counter anti-inflammatories) and marinol (cannabinoid medication)
  • Psychiatric medications: antidepressants, antipsychotics, anxiolytics and ADHD medications
  • Hormonal medications: birth control and other medications containing estrogen or testosterone
  • Diabetes medication[3]
  • One meta analysis found that between 10% and 14% of people taking SSRI’s, a type of antidepressant, deal with night sweats as a result. The use of these types of medications are extremely widespread making them a common culprit of night sweats.[6]

    Neurological Diseases

    Various neurological diseases can cause night sweats to occur. These include:

  • Posttraumatic syringomyelia
  • Stroke
  • Autonomic neuropathy
  • Autonomic dysreflexia
  • Parkinson’s disease
  • The list above is not exhaustive and there are other neurological conditions that can cause night sweating.[1]

    Other Possible Reasons

    There are some other possible causes of night sweats that include conditions like obesity, gastrointestinal reflux disease (GERD), cardiovascular disease, and others. If you are not sure why you are experiencing night sweats it is important to speak with your doctor and rule out some of the more serious potential causes.[5]

    Sources
    1. 8 Causes of Night Sweats. (n.d.). Retrieved August 12, 2019, from https://www.webmd.com/menopause/guide/8-causes-of-night-sweats
    2. Mold, J. W., Woolley, J. H., & Nagykaldi, Z. (2006). Associations Between Night Sweats and Other Sleep Disturbances: An OKPRN Study. Annals of Family Medicine, 4(5), 423-426. Retrieved August 12, 2019, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1578640/.
    3. Pariser, D. M. (2014). Hyperhidrosis (4th ed., Vol. 32). Philadelphia, PA: Elsevier.
    4. Paisly, A. N., & Buckler, H. M. (2010). Investigating secondary hyperhidrosis. BMJ : British Medical Journal (Online), 341. doi:10.1136/bmj.c4475
    5. Davis, K. (2017, December 15). What to know about night sweats. Retrieved August 12, 2019, from https://www.medicalnewstoday.com/articles/296818.php
    6. Giudice, M. (2006). Tracing night sweats to drug can be challenging. . Canadian Pharmacists Journal, 139(1), 59-60. Retrieved August 27, 2018, from http://ezproxy.co.wake.nc.us/login?url=https://search.proquest.com/docview/221185945?accountid=14867