# Sleeping and body temperature

**URL:** <https://boards.straightdope.com/t/sleeping-and-body-temperature/83578>\
**Category:** Factual Questions\
**Created:** [September 24, 2001, 11:14pm UTC](https://boards.straightdope.com/t/sleeping-and-body-temperature/83578 "2001-09-24T23:14:31Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Dignan](https://avatars.discourse-cdn.com/v4/letter/d/f07891/32.png) [@Dignan](https://boards.straightdope.com/u/Dignan)\
**Post date:** [September 24, 2001, 11:14pm UTC](https://boards.straightdope.com/t/sleeping-and-body-temperature/83578/1 "2001-09-24T23:14:31Z")

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When I go to sleep I feel comfortable, but when I wake up I’ll be cold. I’m in a dorm room so it’s a small area and the temperature stays pretty well regulated (about 74 or 75), but I wake up cold. Why is that? Does my body temperature drop that much when I’m sleeping?

This has been bugging me, so a big thank you to whoever can give me the (correct) answer.

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**Author:** ![ModernRonin2](https://avatars.discourse-cdn.com/v4/letter/m/c37758/32.png) [@ModernRonin2](https://boards.straightdope.com/u/ModernRonin2)\
**Post date:** [September 24, 2001, 11:26pm UTC](https://boards.straightdope.com/t/sleeping-and-body-temperature/83578/2 "2001-09-24T23:26:26Z")

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From [http://www.stanford.edu/~dement/temp.html:](http://www.stanford.edu/~dement/temp.html:)

* * *

Body temperature, contrary to the common belief, is not uniformly 98.6°F. That is merely an average. Temperature cycles from about 1 degree below to 1 degree  
above this average over the course of the day. For healthy young adults who sleep at night, body temperature usually is lowest around 4 to 5 a.m. Most sleep  
episodes occur in a window from about 6 hours before the daily low to about 2 hours after it.

Sleep specialist have long debated whether the nighttime drop in temperature induces sleep or follows it. One theory is that is simply the result of lying down and  
curtailing physical activity.

* * *

So there you have it. Although we don’t know why exactly, your body temperature does generally fall during sleep.  
-Ben

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**Author:** ![Gaspode](https://avatars.discourse-cdn.com/v4/letter/g/aeb1de/32.png) [@Gaspode](https://boards.straightdope.com/u/Gaspode)\
**Post date:** [September 24, 2001, 11:26pm UTC](https://boards.straightdope.com/t/sleeping-and-body-temperature/83578/3 "2001-09-24T23:26:37Z")

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There could be a number of factors at work here.

Yes your body temperature does drop when you sleep. Added to that the muscles are relaxed and hence not generating the heat they would be when you’re awake. Even just standing around generates considerable amounts of heat energy. There’s also the fact that quite often you sleep quite a short period after eating, and digestion generates heat by itself. This will have slowed down after 8 hours asleep.

Of course even a drop of 1 or two degrees in room temperature is enpugh to take you from being reasonably conmfortable to being too cold to sleep…

Have you considered investing in a blanket?

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**Author:** ![MsWhatsit](https://avatars.discourse-cdn.com/v4/letter/m/eb8c5e/32.png) [@MsWhatsit](https://boards.straightdope.com/u/MsWhatsit)\
**Post date:** [September 24, 2001, 11:37pm UTC](https://boards.straightdope.com/t/sleeping-and-body-temperature/83578/4 "2001-09-24T23:37:33Z")

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Cecil addressed this as well, at [http://www.straightdope.com/classics/a2\_300.html](http://www.straightdope.com/classics/a2_300.html)

Relevant quote:

> [@](#):
>
> For our purposes, the most important function to be concerned with is body temperature, which is highest at midday and lowest in the early morning hours. (That’s why if you pull an all-nighter you’ll feel chilly around 4 AM, even if room temp stays constant.)