Sweating is normal and a core part of how the body regulates its temperature. In a sauna or working out in the gym, sweating profusely is expected. Waking up sweating in the middle of the night is another matter altogether. Night sweats can be defined as sweating in excess of that required by the body to regulate body temperature.
There are various causes of night sweats, which doctors call “sleep hyperhidrosis.” The issue is often not serious, but it sometimes shows that a person needs medical attention.
Sweating while you sleep is expected when the room is too warm or your blanket is too heavy. But if you find yourself soaked and need to change your sheets or clothes, this is a sign of night sweats and a possible underlying health issue. Excessive sweating during sleep is also linked to other symptoms like fever, weight loss, pain, cough, and diarrhea,
Doctors often hear their patients complain of night sweats. Night sweats refer to excess sweating during the night. But if your bedroom is unusually hot or you are wearing too many bedclothes, you may sweat during sleep, and this is normal. 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.
If you experience night sweats, you’re probably all too familiar with waking up damp (or drenched) in sweat. You’ve probably also said to yourself, more than once, “This can’t be normal.”
“It’s normal to experience variations in your body temperature while you sleep, and sometimes this can lead to sweating,” says Dr. Aarthi Ram, neurologist and sleep medicine expert at Houston Methodist. “While they’re understandably annoying, night sweats are sometimes harmless — and there are steps you can take to reduce the amount you sweat while you sleep.”
What Are Night Sweats?
Doctors in primary care fields of medicine often hear their patients complain of night sweats because they are common. Night sweats refer to any excess sweating occurring during the night. However, if you keep your bedroom temperature unusually hot or you are sleeping in too many clothes, you may sweat during your sleep, which is normal. In order to distinguish night sweats that arise from medical causes from those that occur because one’s surroundings are too warm, doctors generally refer to true night sweats as severe hot flashes occurring at night that can drench sleepwear and sheets, which are not related to an overheated environment.
In one study of 2267 patients visiting a primary care doctor, 41% reported experiencing night sweats during the previous month, so the perception of excessive sweating at night is common. It is important to note that flushing (a warmth and redness of the face or trunk) also may be hard to distinguish from true night sweats.
Reasons You Get Night Sweats
Menopause is when women permanently stop having their period. During this time, significant changes in the body’s production of the hormones estrogen and progesterone are believed to be an important driver of hot flashes
Hot flashes are considered to be a hallmark of menopause, affecting up to 85% of women. In most cases, hot flashes actually begin in the transition time before menopause, known as perimenopause, and can continue once a woman is postmenopausal.
Menopausal hot flashes normally last for a few minutes and can occur multiple times per day, including at night, when they can cause night sweats. It’s common for hot flashes to continue occurring for several years, and some women experience them for more than two decades.
Perhaps not surprisingly, many women — up to 64% — report sleeping problems and higher rates of insomnia during perimenopause and menopause. While night sweats are not the only cause of these sleeping difficulties, they can contribute to poor sleep, especially when they are severe.
Drinking Before Bedtime
Having a drink or two in the evening may sound relaxing, but it can lead to increased body temperature — and therefore sweating.
“While alcohol is often referred to as a ‘depressant,’ it’s not really that simple,” Dr. Ram explains. “Alcohol relaxes the airways, which can make breathing harder. In addition, it also acts as a stimulant in that it leads to increase heart rate. Both of these can increase your body temperature.”
If you suffer from night sweats, Dr. Ram recommends limiting alcohol before bedtime.
Hormonal disorders can make it difficult for your body to regulate its normal temperature, which can cause night sweats.
Body temperature is regulated by the hypothalamus, an area in the brain that produces hormones. When your hormones are out of balance, it sometimes means that the hypothalamus isn’t able to regulate temperature correctly.
Hormonal disorders that can affect body temperature and cause night sweats include:
- Hyperthyroidism. This condition leads to overproduction of the thyroid hormone, which causes increased sweating, including night sweats.
- Pheochromocytoma. This is a tumor on the adrenal gland which makes it produce too many hormones. Symptoms can include night sweats and elevated heart rate.
- Carcinoid syndrome. This is a rare disease linked to tumors in the endocrine system. In some cases, it can lead to excess production of the neurotransmitter serotonin. One of the symptoms is excess sweating.
If you experience other symptoms of a hormonal imbalance, such as weight changes or headaches, talk with your doctor about these symptoms.
You’re Having Nightmares
This is probably the simplest explanation for those sweats. “If the sweating is chronic…sometimes it can be that the patient is totally healthy and is actually running in a dream, or frightful in a dream,” says Harry Banshick, MD. “The sweat is the consequence of acting out the dream.”
Dr. Shah agrees, saying that anything that causes “a sympathetic surge” (also known as a fight-or-flight response) can lead to sweating. If you’re having ongoing, persistent nightmares, see your doctor to find out what might be causing it (stress is a big culprit).
When worry grows out of control, one of the physical signs is sweating—during the day and at night. It’s normal to feel anxious sometimes, especially in stressful situations. But ongoing worry that affects your everyday life could be a condition called generalized anxiety disorder. Here are some other physical and emotional symptoms:
- Difficulty sleeping
- Tense or achy muscles
- Nausea, diarrhea, or irritable bowel syndrome
- Trouble making decisions
- Restlessness and trouble relaxing
- Lack of concentration
Certain medications are known to be associated with night sweats. These include some antidepressants known as selective serotonin reuptake inhibitors (SSRIs), steroids, and medicines taken to lower fevers, such as aspirin or acetaminophen, that may paradoxically cause sweating.
Caffeine intake can be a cause of generalized sweating. Alcohol and drug use can also increase the risk of night sweats.
Your Sleepwear And Sleep Environment
Everyone likes a cozy sleep environment. But, sometimes, there’s a fine line between being cozy and overheating.
Dr. Ram says that the most common reason for night sweats are:
- Bedding, sleepwear or even a mattress that doesn’t “breathe”
- A sleep environment that’s too warm
“In fact, if you’re sweating excessively at night for these reasons, we don’t actually consider it true night sweats,” says Dr. Ram.
Dr. Ram’s tips for avoiding overheating while sleeping:
- Keep your bedroom cool. Lower your thermostat and/or leverage a fan.
- Dress light. Don’t overdress and choose moisture-wicking materials if you need to.
- Choose lightweight bedding. Avoid fleece, flannel, down and synthetic fibers.
- Consider your mattress. Foam materials can limit airflow.
If you’re sick with a viral or bacterial infection, your body raises its internal temperature to fight off the infection, which is what causes fever.
This increase in body temperature can lead to sweating — and night sweats are a common symptom associated with fevers.
“Various infections such as HIV, tuberculosis, and infectious mononucleosis can cause night sweats,” Mandal says. “These conditions can produce chemicals called cytokines which combat infection. Cytokines can induce fever and night sweats.”
If you experience a fever in addition to night sweats, you may want to check in with your doctor about what type of infection you have.
You’re Taking Antidepressants
Patients taking antidepressants can definitely see an uptick in night sweats, Dr. Shah says, as certain classes of medications can cause an adrenergic reaction, which has to do with your adrenaline levels and leads to sweating. If you’re taking venlafaxine (or the brand-name Effexor) or bupropion (or its brand-named Wellbutrin, Zyban, or Aplenzin), you may experience more night sweats, Dr. Shah says.
But there’s good news if you don’t want to switch your antidepressant, as Dr. Shah says there are drugs docs can prescribe to calm down the adrenergic output, which won’t counteract your mental health care.
Gastroesophageal reflux disease (GERD), or chronic acid reflux, is a common condition in which stomach acid regularly flows back into the esophagus—the tube that links the mouth and stomach. When food makes it to your stomach, a valve at the end of the esophagus has trouble closing well and allows acid backwash to stream back up through your throat and mouth. Night sweats are one symptom of GERD. Others include:
- Swallowed food returns to your mouth (regurgitation)
- A sensation of food stuck in your throat
- Chest pain
- Trouble swallowing
- Throwing up
- Sore throat and raspy voice
Changes in the endocrine system, which controls hormone levels in the body, can be related to night sweats. Examples of hormone problems with links to night sweats include overactivity of the thyroid (hyperthyroidism), diabetes and elevated blood sugar, and abnormal levels of sex hormones.
The part of the brain that regulates body temperature is known as the hypothalamus, and it is also involved in the endocrine system. Hypothalamic dysfunction may be an underlying issue related to hormone imbalances and night sweats.
Other conditions affecting the endocrine system such as pheochromocytoma (a tumor of the adrenal gland) and carcinoid syndrome (caused by slow-growing tumors that produce hormones) can also be associated with night sweats.
You Have A Sweating Disorder
While incredibly rare, it’s possible you may suffer from hyperhidrosis — a condition in which your body produces excessive sweat for unknown reasons.
Dr. Ram’s tips for individuals with hyperhidrosis:
- Invest in quality antiperspirants. Also, keep in mind, deodorants do not reduce sweating.
- Consider your clothing. Opt for loose-fitting clothes that are more breathable, such as those with open knit or loose weave, made with thin materials, moisture-wicking or quick-drying properties, or containing mesh panels or air vents.
- Avoid heavy shoes and tight socks. If you sweat from your feet, choose shoes that use little to no synthetic materials and socks that are moisture-wicking.
“Less than 3% of the population suffers from primary hyperhidrosis, and the cause is typically unknown. This isn’t a serious condition, but it can be embarrassing,” says Dr. Ram. “However, several medical conditions, some of which are potentially serious, can cause what’s called secondary hyperhidrosis.”
You Have Undiagnosed Lymphoma
Lymphoma—a cancer of part of the immune system, according to the U.S. National Library of Medicine (NLM)—can cause multiple symptoms like fever, changes in weight loss, and, yes, night sweats, says Dr. Shah. Essentially, your body recognizes lymphoma as something it needs to fight off, and raises its temperature to try to do so, she adds.
While these “soaking sweats,” per the NLM, happen at night, heavy sweating might occur during the day for this, too, so get to your MD if you’re experiencing any other symptoms and they can test you for the condition, says Dr. Shah.
One of the most common signs of this sleep disorder is night sweats. Sleep apnea happens when breathing is disrupted while you sleep. Left untreated, the condition stops your breathing several, sometimes even hundreds of times a night. It affects about 25% of men and tends to happen more in people over 50 who carry extra weight.
Sleep apnea happens when the tongue and soft tissue at the back of the throat block the airway (obstructive sleep apnea), and in people with disorders of the central nervous system such as a stroke or ALS (central sleep apnea). Besides night sweats, signs of sleep apnea include:
- Sleepiness during the day
- Restlessness and waking up many times a night
- Waking up choking or gasping
- Dry mouth or sore throat when you wake up
- Forgetfulness, irritability, and difficulty focusing
- Depression or anxiety
- Waking up several times a night to use the bathroom
- Sexual dysfunction
Sleep apnea is associated with other health problems such as high blood pressure, stroke, and diabetes, so talk to a healthcare provider if you notice any of these symptoms.
You Have An Underlying Medical Issue
In some cases, night sweats occur as a result of a medical condition or disease, including:
- Autoimmune disorders, such as rheumatoid arthritis
- Cancers, including leukemia, lymphoma and prostate cancer
- Heart disease
- Hyperthyroidism (also known as an overactive thyroid)
- Prostate cancer
- Serious infections, such as endocarditis and tuberculosis
- Sleep disorders, including obstructive sleep apnea
“Sleeping and sweating are both very complex processes that respond to many cues, and they can definitely influence one another,” says Dr. Ram. “If you’re regularly waking up soaked in sweat, experiencing sudden night sweats accompanied by weight loss or if your night sweats are keeping you from getting quality sleep, it’s time to talk to your doctor.”
While not a direct cause of night sweats, low testosterone levels are connected to other conditions like sleep apnea, which can set off excessive perspiration while you sleep.
One study found that men with severe sleep apnea had lower testosterone levels and a higher chance of erectile dysfunction than those who snored or had only mild sleep apnea. And, other research shows men with low testosterone get less restful sleep and tend to be overweight, which can make night sweats worse.
Cancer and Cancer Treatment
In certain cases, night sweats could be a sign of cancer. “Certain malignancies such as lymphoma or solid organ cancers can lead to excessive night sweats,” says Anis Rehman, MD, the medical director at District Endocrine and a member of the SingleCare Review Board. “Hence, it is essential to pay attention and seek medical attention if one has drenching night sweats.”
Cancer treatments such as radiation therapy and chemotherapy can also lead to night sweats. Men who have surgery to remove one or both testicles after a prostate cancer diagnosis may notice them. Hormone therapy to treat prostate cancer is also a trigger for this common symptom.
Unfortunately, night sweats may be around long-term—those who have finished with treatment could still have them.