Sweating at Night: Uncover Why You're Overheating in Sleep

Night sweats or sweating in your sleep is usually from something harmless, such as sleeping in a room that’s too warm or having bad dreams. It can also be a symptom of menopause, drinking alcohol, being under stress, eating spicy foods, or a side effect of a new medication. But sometimes, night sweats occur due to a more serious medical condition, such as an infection, diabetes, or cancer.

Night Sweats as a Medical Symptom

Night sweats are considered a medical symptom when you have repeated episodes of excessive sweating during sleep, and the persistent night sweats cause sweating that is severe enough to soak through your night clothes and/or bedding.

Night sweats are not a disease but can be a symptom of an underlying illness. When night sweats are caused by a health condition, they are frequently accompanied by other symptoms, such as pain, cough, fever, diarrhea, or unexplained weight loss.

How to Distinguish Between Normal Sweating and Night Sweats?

Your sleeping environment can occasionally trigger night sweats. For example, if your air conditioning isn’t working, your bedroom is too warm, or you’re sleeping under too many layers, this may result in excessive sweating during the night. Although these situations can cause heavy sweating, this increased sweating isn’t considered night sweats. In such cases, sweating is nothing more than a normal cool-down response that keeps your body temperature at a comfortable level.

In contrast, night sweats caused by an underlying medical issue can leave you feeling uncomfortable. You may wake up suddenly, feeling a wave of heat spreading throughout your body, followed by a cold sweat. The heavy sweating may be accompanied by red skin, a fast heartbeat, and rapid breathing.

The Science Behind Sweating in Your Sleep

Core Body Temperature

The human body has a core temperature that ranges between 98°F and 100°F, but can vary slightly depending on age and how you are checking body temperature. Normal temperature changes occur when the body reacts to things like exercise and weather in daily life. However, changes in core temperature beyond this range make it harder for the body to function. If your body temperature falls below 95°F, it can cause hypothermia. If your temperature goes above 107°F, it can cause hyperthermia. Both are serious conditions that can be fatal.

Thermoregulation in the Human Body

The process by which the human body maintains its core temperature is called thermoregulation. Some of the ways in which the body can regulate body temperature include:

Sweating: When you’re overheated, liquid is secreted from your sweat glands, allowing heat to escape and lowering your temperature.
Cutaneous vasodilation: If you’re hot, your body sends more blood to your skin to dissipate heat (this is what causes your skin to become red).
Shivering: When you’re feeling cold, your muscles shiver to produce heat through muscle contractions.
Cutaneous vasoconstriction: If you’re cold, blood vessels in your skin become narrower to reduce blood flow and retain heat.

Body Temperature Regulation and Sleep Quality

Both the temperature in your sleeping environment and your core temperature can affect the quality of your sleep. Your core temperature rises and falls throughout the day and follows a circadian rhythm, typically in an S-shaped curve. It is typically low in the early morning hours, followed by a sharp rise upon waking hours. As the evening approaches, the body temperature starts to drop again. This drop in core temperature in the evening is a signal for your body to prepare for sleep. That’s why a warm bath before bedtime can make falling asleep easier and lead to more restful sleep by lowering your core temperature.

Impact of Sleep Cycles on Core Temperature

Researchers believe the body’s thermoregulatory mechanisms and sleep are closely connected. The body appears to become cooler as it transitions from wakefulness to the first round of non-rapid eye movement (NREM) sleep during the natural sleep cycle. There is also a rewarming of the body when it transitions back from REM sleep to wakefulness. Scientists believe this coordination between the circadian rhythm, core temperature, and sleep cycle is important for restful sleep.

Causes of Night Sweats

The underlying cause of night sweats can range from the relatively harmless to serious and rare causes. The most common causes of night sweats are listed below.

Hormonal Changes in Women

Night sweats and hot flashes are common in women going through perimenopause and menopause. They occur due to hormone imbalances, which affect the hypothalamus, the part of the brain that acts as the body’s internal thermostat.

Hormonal fluctuations during the menstrual cycle can similarly cause night sweating and other symptoms like irritability and cramps. A drop in estrogen levels is responsible for these symptoms, which are called premenstrual syndrome (PMS) or premenstrual dysphoric disorder (PMDD).

Changes in hormone levels during pregnancy can also cause night sweats. They are more likely to occur in the first and third trimesters and may continue for a few weeks after childbirth.

Other Hormonal Conditions

Hormonal conditions in both men and women can lead to night sweats, such as diabetes, primary hyperparathyroidism (too much parathyroid hormone), thyroid disorders (underactive or overactive thyroid), and endocrine tumors. Learn more about what causes night sweats in men.

Infectious Diseases

Night sweats can be a symptom of both common and serious infections, such as the common cold, influenza, COVID-19, tuberculosis, endocarditis, osteomyelitis, pyogenic abscess in the liver, and HIV (human immunodeficiency virus).

Neurological Disorders

Certain conditions of the nervous system can cause night sweats. For example, stroke, syringomyelia, autonomic neuropathy, and autonomic dysreflexia.

Cancer

Night sweats can be a symptom of some blood and bone marrow cancers, such as lymphomas and leukemias.

Mental Health Conditions

People with anxiety or panic disorder can get night sweats. Sweating at night can also occur in people with substance use disorders, including those using alcohol, heroin, or cocaine.

Sleep Disorders

Night sweats can be a symptom in people with untreated obstructive sleep apnea (OSA), caused by higher cortisol levels when breathing is interrupted. An expert in sleep medicine can make a diagnosis of OSA, and treatment may be necessary.

Gastrointestinal Conditions

Although the direct cause is unknown, conditions such as gastroesophageal reflux disease (GERD) are associated with night sweats in some people.

Sweating Disorders

Some people experience night sweats related to hyperhidrosis, a condition in which there is excessive sweating without any identifiable cause.

Medication Side Effects

Many medications can cause night sweats as a side effect, including cancer treatments like tamoxifen, steroids, some diabetes medications, certain antidepressants such as selective serotonin reuptake inhibitors (SSRIs), over-the-counter painkillers such as acetaminophen and aspirin, and medications used to treat a medical condition such as high blood pressure.

When To See a Doctor for Night Sweats?

If your night sweats cannot be explained by your environment, such as a warm room temperature, there may be an underlying health condition causing them.

Make an appointment to see your health care provider if you regularly experience night sweats (if you regularly wake up with your night clothes and bedding soaked with sweat).

In rare cases, the presence of other concerning symptoms can be a sign of something more serious going on. In addition to night sweats, other cancer symptoms include:

Fatigue
Unexplained weight loss
Swelling or lumps in any part of the body
Severe, persistent, or worsening pain anywhere in the body
Cough
Hoarse voice
Unusual bleeding or bruising
Changes in bowel or bladder habits
Fever
Headaches
Trouble sleeping
Vision or hearing problems

It’s likely that the root cause of your night sweats is a health condition that can be easily treated. Your doctor will obtain a medical history, perform a physical exam, and order blood tests and imaging studies to find out what’s causing your symptoms.

Treating and Managing Night Sweats

Treatment for night sweats will depend on the underlying cause. Most of the causes of night sweats are treatable conditions. For example, replacement hormone therapy during menopause can be used to balance hormone levels and provide relief from night sweats. Your healthcare provider can make a proper diagnosis and recommend the appropriate treatment.

Once the root cause has been found, there are several things you can do to manage night sweats, in addition to taking the prescribed treatment from your doctor.

Set the thermostat in your bedroom at a comfortable temperature. Experts say the best room temperature for comfortable sleep is 65 to 68 degrees Fahrenheit (approximately 15-20 degrees Celsius).
Wear lightweight, loose-fitting cotton or linen nightclothes.
Use layered, moisture-wicking bedding that can be adjusted as needed.
Use mattress covers and pillows that contain cooling gels.
Place a cold pack under your pillow and flip it over during the night so that your head is on the cooled surface.
Keep some cool water on your bedside table to sip on during the night.
Avoid night sweat triggers such as spicy foods, alcohol, caffeine, nicotine, and exercising before bedtime.
Practice good sleep hygiene and relaxation techniques before bedtime to promote restful sleep.

Common Questions About Night Sweats

Why am I sweating at 3 AM?

You may be sweating at 3 AM because you are wearing too many layers, covering yourself with too much bedding, or sleeping in a bedroom that is too warm. These are the most common causes of sweating at night.

When should I be worried about night sweats?

You should be worried about night sweats if:

You have repeated episodes of heavy sweating that cannot be explained by your sleeping environment.
You have other symptoms accompanying your night sweats.