# Why do I sweat when I sleep? **URL:** \ **Category:** Factual Questions\ **Created:** [August 29, 2009, 3:39am UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118 "2009-08-29T03:39:55Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![tzimmerman](https://avatars.discourse-cdn.com/v4/letter/t/278dde/32.png) [@tzimmerman](https://boards.straightdope.com/u/tzimmerman)\ **Post date:** [August 29, 2009, 3:39am UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/1 "2009-08-29T03:39:55Z")
When I wake up, especially from a nap during the day, I usually am drenched with sweat like I just ran a 5k, even when the ac is blasting. What’s the deal with that? I though body temperature goes down when you sleep. ---
**Author:** ![Bruce\_Wayne](https://avatars.discourse-cdn.com/v4/letter/b/22d042/32.png) [@Bruce\_Wayne](https://boards.straightdope.com/u/Bruce_Wayne)\ **Post date:** [August 29, 2009, 3:53am UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/2 "2009-08-29T03:53:19Z")
Because you have either [HIV, cancer, tuberculosis or a host of other diseases](http://en.wikipedia.org/wiki/Night_sweats). 😉 ---
**Author:** ![minor7flat5](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/minor7flat5/32/258_2.png) [@minor7flat5](https://boards.straightdope.com/u/minor7flat5)\ **Post date:** [August 29, 2009, 4:03am UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/3 "2009-08-29T04:03:32Z")
I’m the same way and my assumption has always been that it is a result of two things: some strange metabolism thing happening in our sleep combined with the stillness of the surrounding air. I find that even in relatively cool air, I cannot get to sleep unless there is a fan stirring things up. It’s as if a blanket of stuffy air accumulates around me unless there is some active ventilation happening. ---
**Author:** ![IAmNotSpartacus](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@IAmNotSpartacus](https://boards.straightdope.com/u/IAmNotSpartacus)\ **Post date:** [August 29, 2009, 4:13am UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/4 "2009-08-29T04:13:49Z")
> [@Bruce\_Wayne](#): > > Because you have either [HIV, cancer, tuberculosis or a host of other diseases](http://en.wikipedia.org/wiki/Night_sweats). 😉 You sure 'bout that, doc? ---
**Author:** ![kelly5078](https://avatars.discourse-cdn.com/v4/letter/k/6f9a4e/32.png) [@kelly5078](https://boards.straightdope.com/u/kelly5078)\ **Post date:** [August 29, 2009, 4:34am UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/5 "2009-08-29T04:34:56Z")
I don’t know, but I do it too. Not all the time, and sometimes it’s because I feel cold, put on a blanket, then warm up in my sleep. But most of the time I have no idea. I find that using melatonin as a sleep aid causes me to sweat more, so if you do that, it might be a factor. ---
**Author:** ![Bruce\_Wayne](https://avatars.discourse-cdn.com/v4/letter/b/22d042/32.png) [@Bruce\_Wayne](https://boards.straightdope.com/u/Bruce_Wayne)\ **Post date:** [August 29, 2009, 5:09am UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/6 "2009-08-29T05:09:05Z")
> [@IAmNotSpartacus](#): > > You sure 'bout that, doc? No, I’m not, I was just being stupid. I looked up the same question a few months back because of my own night sweats. The wikipedia article scared the crap out of me. There were no harmless explanations. I’m sure I don’t have any of those diseases listed and I’m not a woman, so its not menopause. [Here](http://yourtotalhealth.ivillage.com/what-causes-night-sweats.html) is another site. TB gets mentioned again. Ouch. ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [August 29, 2009, 5:19am UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/7 "2009-08-29T05:19:55Z")
FWIW, I often wake up from naps a bit sweaty. (Maybe 20% of naps.) I also only ever drool during naps. (\<20% of naps.) During a proper night’s sleep: all dry, more or less. Been like that as long as I remember. ETA: Also, extreme jetlag-y sleep usually leads to my sweating… ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [August 29, 2009, 5:55am UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/8 "2009-08-29T05:55:01Z")
Turn down the temp on the AC. I can’t get a good night’s sleep unless it’s ~70ºF. Actually, I find I get sweaty more in the winter, because we have the heat cranked up, and maybe an extra blanket on the bed. A fan is a good recommendation too, even a ceiling fan. I didn’t start getting night sweats until I was in my mid-20s. Must be a ‘getting older’ thing. I’m 36 now, and I think I have it under control. But every so often, I’ll wake up and have to get a frikkin’ towel. Just take more care of the ambient temperature, and learn what to set it at to stay dry and comfy. ---
**Author:** ![glowacks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/glowacks/32/5548_2.png) [@glowacks](https://boards.straightdope.com/u/glowacks)\ **Post date:** [August 29, 2009, 6:05am UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/9 "2009-08-29T06:05:26Z")
I attribute it to having blankets so air-tight that your sweat is unable to evaporate. Your body keeps on putting out sweat as it overheats, all of which is there when you wake up. I myself have often needed a towel after waking up at night with a thoroughly socked blanket. If this is the case, the only way to really fix it is to not have blankets that prevent the circulation of air from your body cavity inside those blankets, or at least blankets that allow more heat to escape. Since the purpose of blankets, particularly in winter, is to keep you warm, it seems hard to avoid once your body temperature gets to the point that your body starts sweating. ---
**Author:** ![aruvqan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aruvqan/32/2891_2.png) [@aruvqan](https://boards.straightdope.com/u/aruvqan)\ **Post date:** [August 29, 2009, 12:06pm UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/10 "2009-08-29T12:06:38Z")
> [@glowacks](#): > > I attribute it to having blankets so air-tight that your sweat is unable to evaporate. Your body keeps on putting out sweat as it overheats, all of which is there when you wake up. I myself have often needed a towel after waking up at night with a thoroughly socked blanket. > > If this is the case, the only way to really fix it is to not have blankets that prevent the circulation of air from your body cavity inside those blankets, or at least blankets that allow more heat to escape. Since the purpose of blankets, particularly in winter, is to keep you warm, it seems hard to avoid once your body temperature gets to the point that your body starts sweating. Nope. mrAru sleeps with a bedsheet only and the room is currently airconditioned within an inch of its life and he still sweats. Me, Im going through hysterectomy menopause and am hot flashing when i am jus tsitting here… but he didnt have one [and he has sweat for years at night. he has to sleep with a towel on his pillow] ---
**Author:** ![Bumbazine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bumbazine/32/362_2.png) [@Bumbazine](https://boards.straightdope.com/u/Bumbazine)\ **Post date:** [August 29, 2009, 5:13pm UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/11 "2009-08-29T17:13:57Z")
One condition I didn’t see in the referenced link was diabetes. I don’t remember exactly how it works, but, according to my doctor, it has to do with blood sugar. Google ‘diabetic night sweats’ to get more links than you’ll know what to do with. I know that if I eat or drink anything sweet within 3 or 4 hours before bed, I get night sweats. (Type II diabetic here.) Anyway, ask you doctor to check you next time you visit. ---
**Author:** ![Dallas\_Jones](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dallas_jones/32/3277_2.png) [@Dallas\_Jones](https://boards.straightdope.com/u/Dallas_Jones)\ **Post date:** [August 30, 2009, 4:59am UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/12 "2009-08-30T04:59:55Z")
> [@Bruce\_Wayne](#): > > Because you have either [HIV, cancer, tuberculosis or a host of other diseases](http://en.wikipedia.org/wiki/Night_sweats). 😉 Shit, that means I’ve been dying for over 40 years now. ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [August 30, 2009, 5:13am UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/13 "2009-08-30T05:13:35Z")
I do too. I like a heavy blanket, and so I sweat. Note that my Doc sez I am disgustingly healthy. So, **Bruce Wayne** you are wrong. :rolleyes: ---
**Author:** ![Captain\_Awesome](https://avatars.discourse-cdn.com/v4/letter/c/a698b9/32.png) [@Captain\_Awesome](https://boards.straightdope.com/u/Captain_Awesome)\ **Post date:** [August 30, 2009, 5:44am UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/14 "2009-08-30T05:44:40Z")
Genetic hyperhydrosis is relatively common, affecting about 1-3% of the population. The primary genetic form is not something of medical concern, beyond managing the symptoms (for which their are a variety of options). IIRC it tends to become apparent at or around puberty, so if your onset differs it would be wise to seek a consult to rule out the secondary causes of which there are many. ---
**Author:** ![Paintcharge](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/paintcharge/32/7946_2.png) [@Paintcharge](https://boards.straightdope.com/u/Paintcharge)\ **Post date:** [August 31, 2009, 3:11pm UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/15 "2009-08-31T15:11:23Z")
I need it to be warm in order to not sweat at night. It seems that if my face (outside of the covers) gets cold then my stupid body (inside the covers) overworks in order to warm up. Develops into a fun cycle of waking up cold and sweaty, roll over, rearrange covers, and back to sleep. ---
**Author:** ![Lanzy](https://avatars.discourse-cdn.com/v4/letter/l/74df32/32.png) [@Lanzy](https://boards.straightdope.com/u/Lanzy)\ **Post date:** [August 31, 2009, 4:03pm UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/16 "2009-08-31T16:03:51Z")
I use a light sheet, always have a fan, keep the room at 73F…always sweat. ---
**Author:** ![picunurse](https://avatars.discourse-cdn.com/v4/letter/p/7bcc69/32.png) [@picunurse](https://boards.straightdope.com/u/picunurse)\ **Post date:** [August 31, 2009, 4:21pm UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/17 "2009-08-31T16:21:58Z")
[Night sweats](http://www.medicinenet.com/night_sweats/article.htm) are different than waking up a little sweaty. Night sweats drench the bed, sometimes even the mattress. The above link differentiates between the two. ---
**Author:** ![YogSothoth](https://avatars.discourse-cdn.com/v4/letter/y/8edcca/32.png) [@YogSothoth](https://boards.straightdope.com/u/YogSothoth)\ **Post date:** [September 1, 2009, 7:34pm UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/18 "2009-09-01T19:34:04Z")
Maybe you’ve been having one too many dreams about running from something? ---
**Author:** ![TheMadHun](https://avatars.discourse-cdn.com/v4/letter/t/53a042/32.png) [@TheMadHun](https://boards.straightdope.com/u/TheMadHun)\ **Post date:** [September 1, 2009, 7:37pm UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/19 "2009-09-01T19:37:34Z")
I occasionally sweat. I find it’s usually when I’ve fallen asleep “wrong” either twisted in the bedclothes or with my neck at an odd angle. When I’ve looked it up on the web, the medical consensus seems to be that if it’s not every night for a week, then it’s indicative of nothing, just a fluke, akin to having your leg fall asleep. ---
**Author:** ![MeanOldLady](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/meanoldlady/32/10737_2.png) [@MeanOldLady](https://boards.straightdope.com/u/MeanOldLady)\ **Post date:** [September 1, 2009, 8:24pm UTC](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118/20 "2009-09-01T20:24:32Z")
Do you drink a lot? [Next page](https://boards.straightdope.com/t/why-do-i-sweat-when-i-sleep/508118.md?page=2)