Why does heat make us sleepy when we are tired? We naturally cool down when it’s bed time and we sleep better when our bodies are cool.

171 views

Why does heat make us sleepy when we are tired? We naturally cool down when it’s bed time and we sleep better when our bodies are cool.

In: Biology

I would guess because your body needs to do a lot of work to cool down, so a lot of energy is missing, therefore there’s not enough energy to keep you awake.

Doing things requires energy and making energy generates heat.

The body tries to go into a lower energy state (sleep) so it doesn’t produce as much heat when it’s hot. This reduces the risk of overheating. Some cultures have a siesta where they nap during the hottest part of the day.

When sleeping at night you typically cover yourself with more things than you do during the day (assuming the same temp) because your body produces less heat.

Heat makes your body relax. It goes into energy saving mode to prevent you from spending fluids etc for sweat and heat regulation.

Part of it is a built in “governor” to keep you from overheating. Doing anything involving muscles generates body heat. If you’re already close to overheating, that could be dangerous. So we have evolved a system where the hotter it is, the less you feel like doing. You don’t *know* you’re doing it for health reasons, but the person who feels like napping through the hottest part of of afternoon is stressing their body a lot less than people up doing stuff. Look at all the African animals that nap every afternoon.

It’s similar to night making you feel like sleeping. Humans rely on sight more than most other animals. Other animals have much better smell, heat sensing etc than humans. So for humans, the desire to spend the dark hours tucked in a cave vs. out in the woods is an advantage by making it less likely to be found and eaten by something whose senses give it a big advantage in the dark.