If You're Sweating In Your Sleep, These 5 Unexpected Causes Might Surprise You
by Katy Parker-Shorthouse

Scorching temperatures this summer have lead to sweltering (and at times incredibly sweaty) nights. But what if you're still waking up drenched even though the nights are notably cooler? What causes night sweats? Let's look at five unexpected things that could be causing you to drench your sheets.

You wake up exhausted, your pyjamas, and bed linen are soaked and you've got to change the sheets again. It's a wearisome tale that affects more people than you'd think. A 2014 study found that around 3 percent of the U.S. population suffer night sweats, and according to, in one study of 2,267 patients visiting a primary care doctor, 41 percent of the group complained of experiencing excessive sweating while they were sleeping.

But what exactly are night sweats and when should you be concerned? When a person sweats normally, it's the body reacting to being too hot; your body produces a water-type liquid which consequently evaporates, taking some of the body's heat with it, as reported by Live Science. For some people sweating too much in the night could be your body simply responding to overheating — perhaps your room is too hot or you're going a bit OTT on your nightwear (fleecy pyjamas and sheepskin socks anyone?)

Michael Grandner, an associate professor and director of the Sleep & Health Research Program at the University of Arizona College of Medicine told Time magazine that your core temperature drops during the hour or two before bed thanks to your body's built-in sleep clock, and continues to drop until it reaches its lowest point at around 3 a.m. Thick pyjamas and heavy blankets will trap heat around your body, raising your body temperature and impacting this natural cooling process, and therefore disrupting a quiet night's rest.

But it could also point to something more serious. If your room is at a normal temperature and you're still waking up drenched in sweat, you could be suffering from what doctors refer to as "true night sweats," according to WebMD when, regardless of the temperature of the room, you are suffer from severe hot flashes in the night that leave your bedsheets soaked. You don't have a fever, you're too young for the menopause, so what could it be? Here's a rundown of the five underlying causes of night sweats that you might not expect.


Hormonal Imbalances

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Cue the eye roll. Hormones, the bane of all our lives, could be the cause of your night sweats too, and it's not just menopausal women who are likely to be affected. If you're approaching your period, pregnant, or going through puberty, these hormonal shifts can cause a rise in body temperature and result in nighttime hot flashes, according to Metro. Dr Hadine Joffe, an associate professor in the division of sleep medicine at Harvard Medical School told Time magazine that these changes can also cause “mini arousals” — i.e. periods of really light sleeping — which can leave you feeling more tired during the day.



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If you're on medication for a pre-existing condition, turns out this could the root of all your problems. Anything from anti-depressants, insulin, and pain relievers to steroids and hormone-blocking drugs used to treat certain cancers can affect your ability to sleep through the night. According to, 8 to 22 percent of people taking anti-depressant drugs have cited night sweats as a side effect, and WebMD reports that even seemingly innocuous medicines such as aspirin taken to lower a fever can cause your body temperature to rise and lead to night sweats.



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It may seem a bit like a case of chicken and egg, but studies have also found a link between insomnia and night sweats. A 2011 study published in the Journal of Clinical Sleep Medicine suggested a person struggling to sleep — who is agitated and overwhelmed with thoughts of an impending deadline or the presentation they have to give in the morning — is likely to be experiencing a release of the stress hormone cortisol, which could cause your body to produce more heat and then to sweat in an attempt to cool itself down.



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According to Anxiety UK, a staggering 3 million people in the UK are currently suffering from anxiety. And while it has obvious impacts on your day-to-day life, it can affect your sleep as well, with Anxiety Centre confirming that anxiety can cause night sweats. Anxiety coaches Jim and Marilyn Folk, write that this can be put down to a range of physiological and psychological factors. It could be the result of a "fight or flight" stress response, which causes your heart rate and metabolism to increase, making you perspire throughout the night. Anxiety could also cause nightmares, as Jim and Marilyn explain: "Being afraid in nightmares can activate the stress response and its resulting changes, which can include profuse sweating that is experienced as night sweats."



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Did you squeeze a HIIT class in before bed? Did you overdo it in your after-work spin class? This could be the cause of your night sweats, as a 2011 study carried out by Dr James Mold, emeritus professor of family and preventive medicine at the University of Oklahoma College of Medicine, found. Looking at all the possible causes of night sweats, Mold found that anything that disrupts the body's natural thermoregulation process before bed can affect your sleep. He told Time magazine, "One thing we did find is that sweating at night is associated with states of arousal." Grandner elaborated, telling the publication that eating or exercising before bed can "throw off" your body's natural cooling down process, firing up your metabolism and increasing heat production.


The answer? First try opting for cooler, more breathable bedding: that includes your mattress, mattress topper, and duvet. And it may seem like an age-old trick, but sticking a foot out the duvet can really help, as Grandner told Time: "The bottom of the feet have important temperature-sensing functions and can help the body maintain a cool sensation even under a warm blanket." If the problem persists, I suggest you see a doctor to see if you can solve it once and for all. Then you can enjoy sweet dreams, sweat-free.