Why We Get Sweaty in Our Sleep

If you have ever awakened drenched in sweat, you might wonder: Why do we get sweaty in ​our sleep? If it occurs repeatedly, it may be associated with other medical conditions and may require further evaluation. It also may mean different things in children and even in women going through menopause. Discover some of the reasons why we get sweaty in sleep.

First, the most common reason you might get sweaty at night is because of an elevation in body temperature due to a warm sleep environment. If your bedroom has the thermostat cranked, if you are wearing heavy fleece pajamas, or if you are buried under blankets and comforters, it’s no surprise if you become too warm and start to sweat. This is clearly normal.

There are also normal variations of the body temperature throughout sleep. Most people will experience a dip in the core body temperature towards morning, often around 4 a.m. Moreover, during certain phases of sleep, the autonomic nervous system (which controls body temperature, heart rate, blood pressure, and other factors) may become revved up and lead to some sweating. Sweating actually decreases during rapid eye movement (REM) sleep, despite an increased temperature in several parts of the brain, increased brain glucose metabolism, increased skin sympathetic activity, and increased heart rate.

It should be no great surprise that disorders that affect sleep could also lead to night sweats as they occur at the same time. The most common is sleep apnea. If you struggle to breathe during sleep, this will lead to increased effort and work of breathing. Imagine how much you sweat when you are running a race and breathing hard! Each episode of apnea can also provoke a burst of cortisol, the body’s natural stress hormone, to prompt normal breathing. With successful positive airway pressure (PAP) therapy, the occurrence of night sweats may decrease, increasing sleep quality and daytime alertness.

In children, especially toddlers, sleep-disordered breathing may manifest as sweaty and restless sleep. The child may wake red-faced and drenched in sweat with the covers messed up. This should prompt further evaluation, especially if snoring and other signs of sleep apnea are present. Night sweats, accompanied by insomnia, could be an indicator of increased risk of obstructive sleep apnea.

Women may have an increased incidence of hot flushes (or flashes) during sleep as they transition through early menopause. Between postmenopausal and premenopausal women, postmenopausal women report having poorer sleep quality due to insomnia caused by night sweats and hot flashes. Interestingly, the risk of obstructive sleep apnea increases significantly at this time due to the loss of the hormones estrogen and progesterone. Therefore, night sweats in older women may occur with menopause as a result of sleep apnea.

Some people notice they get sweatier in sleep after drinking alcohol. Alcohol dependency, in particular, may cause sweating at night. Alcohol is a muscle relaxant that may affect the upper airway and worsen snoring and sleep apnea. Therefore, the consumption of alcohol may be linked to night sweats through sleep-disordered breathing like apnea.

Finally, nightmares and generalized anxiety may also provoke panic attacks and sweatiness during sleep. If you have recurrent bad dreams, especially in the setting of post-traumatic stress disorder (PTSD), treatment may be helpful. Children may also become sweaty while experiencing night terrors.

There are multiple other causes of night sweats that should be considered. Isolated incidences are less worrisome, but chronic sweating at night may require additional evaluation. If you have other symptoms or signs, such as fevers and weight loss, it may be important to speak with your doctor about the need for further testing. Some of the other potential causes of night sweats include:

• Infections (including tuberculosis)
• Medications (antidepressants, hormone replacement, insulin)
• Hyperthyroidism
• Diabetes (hypoglycemia from medications)
• Autonomic disorders (affecting the brain or nervous system)
• Other causes

Occasionally sweating while sleeping can be completely normal and caused by the environment or even your phase of sleep. Importantly, night sweats can be associated with sleep disorders, like sleep apnea and night terrors. There are several other medical causes of night sweats that, when accompanied by other symptoms, may need further attention.

If you are concerned about recurrent night sweats, talk to your doctor about some of the potential causes of sweaty sleep and whether you need further evaluation with a sleep study or other testing.