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Why do I Heat up When I Sleep?

ChiliSleep Staff


Why do I Heat up When I Sleep?
Do you go to bed at a comfortable temperature then end up waking up hot and sweaty? The cause could be either your bed is too hot or your room temperature is. Find out more in this article.

"Why do I heat up when I sleep?"

We’ve all been there. One minute you’re snuggled up in your bed, lulling off to La La Land, and the next you’re wide awake, kicking off blankets, sweating like you ran a marathon. So why is it that we can fall asleep so comfortably warm and cosy to wake up an hour later baking?

Answer: Most likely, your room/bed is too warm

While overheating during sleep and night sweats can be caused by medical conditions, the most common reason is a sleeping environment that is too warm.

(Note: if your AC has been cranked to subzero temperatures for weeks, and you can’t remember the last time you used a blanket, you should consult your doctor to make sure this is not indicative of a more serious medical issue.)

“But I don’t feel hot when I fall asleep!”

That is because your body temperature drops during sleep which releases heat to the surrounding area. If you pile on ten thousand blankets or dress for bed like Ralphie’s little brother in “The Christmas Story,” it’s no wonder you wake up a little toasty.

(Image courtesy of

That said, certain materials can trap heat more than others. So, while you may love that Sherpa lined wool blanket and your flannel pyjama set with those fuzzy plush socks, those may be what’s locking the heat around you and making it hard to sleep.

“Why is my body cooling down in the first place?!”

Picture it. You are a majestic prehistoric man or woman just chilling in your cave. The sun starts to go down, the temperature begins to drop, and suddenly your brain says, “Hey, sleeps sounds like a good idea.” That’s how we have been wired since the beginning of time. Cooler body temperature signals our brain to close up shop and fall asleep. Similarly, higher body temperatures cue our brain to be more alert. Long story short: when your body releases heat to bring your temp down it’s setting you up for a night of awesome sleep.

“Okay, so how do I fix the problem?”

Here are some tips to make your sleep space cooler:

  • Sleep with the thermostat set between 15-19. (Fair warning, this can get pricey in the summertime or if you live somewhere hot).
  • Use breathable bedding like cotton and avoid synthetic fabrics like polyester. These are more tightly woven and trap heat.
  • Wear breathable clothing to sleep. Pyjamas made from Bamboo naturally cool the skin and are 100% biodegradable. Or if natural is your thing, don’t wear anything at all. We won’t judge.
  • Use a temperature regulating mattress pad like chiliPAD or OOLER
  • Take a hot bath an hour or so before bed. Yes, this will raise your body temperature initially, but remember that part where you have to get out of the tub? That is when your body cools down which gets you ready for bed.

About ChiliSleep Staff

ChiliSleep’s award-winning content team -- journalists, writers, and researchers -- report on a mix of innovative scientific studies, emerging sleep tech trends, and personal wellness topics.
Learn more about our ChiliSleep Team.