Sweat is the body's natural cooling mechanism, and it usually kicks in when it's hot outside or when you're exercising. However, there's a time and a place for it, and while most people expect to work up a sweat at the gym, perspiring while sleeping can be uncomfortable and somewhat alarming.
Evaporation is the key cooling element in sweat, which is mostly water and salt. When the warmer water evaporates, a thin layer of cooler water is left on the skin. Most people have 2 to 4 million sweat glands in their bodies, and most of them are located in the armpits, face, palms of the hands and soles of the feet. Because everyone is different, the more sweat glands you have, the more you'll sweat. Men tend to sweat more than women because women's bodies are better at regulating water [source: Phan, Sternberg].
There are two different types of sweat glands in the body: apocrine glands, which are triggered by emotions (think sweaty palms on a first date) and eccrine glands, which are designed to cool the skin. When it comes to night sweating, eccrine glands are the main contributors, although apocrine glands do their part as well.
The body has an internal thermostat known as the hypothalamus, which sets a desired body temperature and activates sweat glands when it gets too high. Hot weather isn't the only type of stimulus that can give the hypothalamus a high reading, though. Internal problems, like bacterial or viral infections, can provoke the portion of the brain to raise body temperature, creating a fever. Certain types of medications, menopause and serious infectious diseases can also send signals to the hypothalamus to start producing sweat.
While there can be many reasons you're sweating at night, learning to recognize the symptoms and the causes will help you understand this condition. Next, we'll talk about why people sweat in their sleep.
Why do I sweat when I sleep?
Nobody likes to wake up in a pool of sweat in the middle of the night, and in order to figure out what might be causing night sweats, it's important to look at all of the possible variables. The first and most obvious thing to consider is temperature and overall comfort of the sleeping environment. Heat isn't the only environmental factor that might cause night sweating; humidity can also play a significant role. Other possible contributors to night sweats could include heavy blankets or pajamas, or general discomfort caused by an old mattress, a loud environment or even bedbugs.
The next thing to look at is your overall health. Has your diet changed? Have you been feeling fatigued? Flu symptoms include fever, which is a normal response to infection. Night sweats can result from a fever associated with a cold or flu symptoms for one or two nights, but beyond that, it could be something more serious.
One of the most common causes of night sweats is hot flashes associated with menopause, which result from hormonal changes in the body. A sudden drop in estrogen production can cause confusion for the hypothalamus (remember: It's the body's thermostat), causing a woman's skin temperature to increase by as much as 6 degrees, almost instantaneously [source: Breastcancer.org].
Most men reading this are probably counting their blessings that they don't suffer the discomfort of hot flashes, but not all men are exempt. Some men who are testosterone deficient, or who are taking testosterone-blocking drugs, can experience similar effects. For example, androgen deprivation drugs, which are often prescribed for prostate cancer, can disrupt the hypothalamus in 70 to 80 percent of men undergoing therapy. Most men are unlikely to admit that they're experiencing hot flashes, but androgen deprivation can lead to night sweats [source: Harvard Medical School].
What else could be making me sweat?
Prostate cancer drugs aren't the only prescriptions that can leave your sheets damp the next morning. Plenty of other prescription drugs can raise your heart rate and cause the blood vessels in the skin to dilate, which can result in heavy sweating.
Several types of medications have been reported to cause night sweats, but antipyretics, or fever-reducing drugs, are the most common. When experiencing flu symptoms, many people take aspirin or acetaminophen (commonly marketed as Tylenol), but although these medications are often effective in reducing fever, they can also cause night sweats. Other medications that can cause sweating at night include antidepressants [source: American Academy of Family Physicians].
Infectious diseases, like tuberculosis and AIDS, are also known to cause night sweats. A persistent fever, which is often accompanied by nighttime perspiration, is often common among people who have tested positive for HIV. Hodgkin's disease, a type of lymphoma, is another infectious disease that often causes a low-grade fever and night sweats in patients.
Drinking alcohol at night is the culprit for some people. Although a glass of wine before bed might help you get to sleep, studies have shown that alcohol-induced sleep is less restful, and that you're more prone to headaches and night sweats if you drink before going to sleep. Alcohol dependence and alcohol withdrawal are also common causes[source: American Academy of Family Physicians].
Another possible factor that could cause nighttime sweating is spicy food. Although it might not give you immediate discomfort while eating it, it takes the body several hours to digest a meal, and during that time. spicy foods like chilies and cayenne pepper can raise the temperature of your skin. Doctors have also identified caffeine as something that can exacerbate sweating for people who already sweat excessively [source: Emedicine].
Some people also have a condition called hyperhidrosis, which causes frequent and excessive sweating both during the day and at night. Only 2 to 3 percent of Americans (more among Asian populations) have hyperhidrosis, but it can cause those select few a great deal of discomfort and embarrassment. If you have ruled out all other possible causes of night sweats, you might be experiencing hyperhidrosis, and you should schedule an appointment with your doctor to talk about it [source: Mayo Clinic].
Natural Solutions to Night Sweats
There are several prescription drugs you can take to deal with night sweats. You can also try to figure out a natural solution to what's making you sweat at night.
The first and most obvious place to look is the thermostat. While most doctors recommend a sleeping temperature of 65 to 72 degrees, everyone is different, and you should experiment to figure out what makes you comfortable. For most people, that means lowering the thermostat, because a mild drop in body temperature tends to induce sleep in many people. If you sleep with a partner who prefers a warmer or cooler temperature, try using several light layers of bedding [source: WebMD the Magazine].
Eliminating probable causes of stress and anxiety is also a good idea. Nervousness, anxiety and sweat are common causes of excessive sweating -- both during the day and at night. So if you're getting married or interviewing for a new job, it's to be expected that you'll sweat a bit more than usual. But if the night sweats continue several weeks after the big day, you should probably get it checked out.
Many men who suffer from night sweats associated with andropause (or male menopause) take black cohosh tea or black cohosh supplements. Black cohosh is a native plant found in many parts of North America that is commonly used in Native American medicine for a wide variety of diseases. Red clover is another medicinal herb that is taken to ease the severity of hot flashes and associated night sweats, though studies have shown inconclusive results [source: Pray ]. Because of a lack of hard data to support it, the use of red clover is somewhat controversial. Still, it is commonly sold at health food stores [source: Office of Dietary Supplements].
Both men and women have been known to take herbal remedies, like sage tea and motherwort, to deal with night sweats. Sage tea is said to be calming and is often taken to help mitigate stress, and motherwort, an herb in the mint family, is said to help the nerves and circulatory system, which both directly affect night sweats [source: Women's Radio].
What treatment options are available? Keep reading.
Common Treatments for Sweating While Sleeping
The first line of defense that most people have against sweat -- during the day or at night -- is antiperspirants. The function of most antiperspirants is to slow down the production of sweat, and they do that by blocking the underarm glands that secrete it. Aluminum ions usually give deodorants their antiperspirant power, and they do that by entering skin cells and causing the glands to shrink and close, preventing sweat from leaving.
Of course, you don't want to rub antiperspirant/deodorant all over your body. For more serious cases of hyperhidrosis and night sweats, doctors often prescribe medicines like Drysol. Like a typical over-the-counter antiperspirant, the active ingredient in Drysol is aluminum, but it contains higher concentrations. Drysol is applied topically to problem areas, like the armpits, feet, hands and other parts of the body that produce a lot of sweat [source: Drugstore.com]. The problem with topical antiperspirants that contain aluminum chloride is that they can often cause skin irritation, causing people to stop the treatment [source: Emedicine].
For people with hyperhidrosis, some doctors also prescribe Robinul (glycopyrrolate), which prevents the secretion of various fluids in the body. In recent years, it has been revealed that injections of botulinum toxin, or Botox, can provide relief for excessive sweating. In 2004, the FDA approved the use of Botox to treat excessive underarm sweating, and it's sometimes used on other parts of the body, like the hands, as well. In some very extreme cases, surgery has been prescribed for treatment of hyperhidrosis, in which surgeons make incisions in the armpits and other problem areas.
Most people who suffer from night sweats won't end up going under the knife -- those are very extreme cases of a serious disease. Most people who experience night sweats have them only sporadically, and in many cases, making minor changes to your sleeping environment can cure them.
For some useful links and lots more information about sweating at night, read on.
- American Academy of Family Physicians. "Diagnosing Night Sweats." March 1, 2003.http://www.aafp.org/afp/2003/0301/p1019.html
- American Institute of Physics. "Thoracic Surgeons Operate on Nerves to Stop Hyperhidrosis." Feb. 1, 2004.http://www.aip.org/dbis/stories/2004/14105.html
- BreastCancer.org. "All About Hot Flashes." Jan. 27, 2010.http://www.breastcancer.org/tips/menopausal/facing/hot_flashes.jsp
- Doheny, Kathleen. "Can't Sleep? Adjust the Temperature." WebMD the Magazine. March 29, 2010.http://www.webmd.com/sleep-disorders/features/cant-sleep-adjust-the-temperature
- Drugstore.com. "What is Drysol?" Dec. 5, 2006.http://www.drugstore.com/qxa1067_333181_sespider_is_drysol.htm/
- Harvard Health Publications. "Hot flashes in men: An update." August 2005.http://www.health.harvard.edu/newsweek/Hot-flashes-in-men-An-update.htm
- Karpinski, Richard H. S. "Surgical Treatment of Axillary Hyperhidrosis." Emedicine. July 17, 2009.http://emedicine.medscape.com/article/1296530-overview
- MayoClinic.com. "Hyperhidrosis (excessive sweating)." July 30, 2010.http://www.mayoclinic.com/health/hyperhidrosis/DS01082/DSECTION=symptoms
- McArdle ,William D., Katch, Frank L. and Katch, Victor L. "Exercise Physiology: Nutrition, Energy, and Human Performance." Jan. 15, 2001.
- Office of Dietary Supplements. "Black Cohosh." Nov. 21, 2008.http://ods.od.nih.gov/factsheets/blackcohosh.asp
- Phan, Aimee and Sternberg, Steve. "Sweating is one way to keep your cool." USA Today. May 20, 2005.http://www.usatoday.com/weather/resources/basics/sweating-cools.htm
- Pray, W. Steve. "Nonprescription Product Therapeutics." Second edition. Lippincott Williams & Wilkins, 2006. Page 707. (Oct. 10, 2010).
- ScienceDaily. "'Cool' Imagery Lowers Hot Flashes Through Hypnotherapy." July 14, 2010.http://www.sciencedaily.com/releases/2010/07/100713215202.htm
- Stoppler, Melissa Conrad and Shiel, William C. "Night Sweats." MedicationNet.com. 2010.http://www.medicinenet.com/night_sweats/page3.htm
- Weed, Susan. "Everyone Ought to Have a Little Mother[wort] Around the House." Women's Radio. 2004.http://www.womensradio.com/articles/Everyone-Ought-to-Have-a-Little-Mother%5Bwort%5D-Around-the-House/1879.html