I was recently sick and my body temperature was 38.6°C. It felt like I was in a refrigerator.
So, why do we feel cold when we have a high body temperature? Shouldn’t we feel hot instead?
In: Biology
How is it that bacteria can thrive at normal body temperature, but raising it a few degrees is enough to kill it?
Has bacteria somehow evolved to thrive at the optimal human temperature?
Wouldn’t it have evolved to thrive in slightly warmer body temperatures, over the years?
The feeling of being hot or cold isn’t about what temperature your body is, it’s about the transfer of energy via heat.
If you are losing a lot of heat rapidly, you will feel cold. If you are heating up rapidly, you will feel hot.
The thing that speeds up temperature transfer the most is temperature difference. If your body is 90° and the outside is 50°, you will feel colder than if it was 60° outside because more of your heat is transferring quickly.
> So, why do we feel cold when we have a high body temperature? Shouldn’t we feel hot instead?
We don’t really sense how hot or cold we actually are. What we sense is how much heat we are gaining or losing to the environment around us. When we have a fever, we are losing more heat to our surroundings, so we feel cold.
Here’s how I actually explain to patients:
It’s not what your body temperature is, it’s what the temperature difference is between your body and the room.
Average body temp = ~98f
Average room temp = 72f
That’s a 26 degree difference.
So a fever of 103f in a 72f room would feel like you were normal body temp in a 67f room, both a 31 degree temp difference.
That’s why your body wants to get under a blanket. Your temperature receptors detect the difference and assume it’s the atmosphere that changed.
Because the hot sensor is in the skin, when your body enters acute phase (like during an infection), capillaries in the skin contracted to decrease heat loss, in order to raise core temperature, which, effectively decreased heat supply to skin; thus you might feel cold even if you’re in an fever episode.
You feel coldness because your body is warmer than the air around you. Same reason why you feel hotness when you put your hand near an oven.
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