Why You Feel Tired When It's Hot

[Carl Fredrik Ahl]

Hi,

I have a theory that you get tired when it's hot because there is less oxygen in hot air than in cool air. Is this why you get tired or are there other factors?

[Strange]

21 minutes ago, Carl Fredrik Ahl said:

because there is less oxygen in hot air than in cool air.

Do you have any evidence for this?

21 minutes ago, Carl Fredrik Ahl said:

or are there other factors?

I would guess it could be due to the relative efficiency of various metabolic processes at higher temperature.

Or maybe the difficulty of dissipating heat means that the body's natural response is to slow down in oder to control body temperature - it makes us feel tired to stop us generating more heat.

Just found this, which confirms my latter guess: https://www.livescience.com/60116-why-heat-makes-you-feel-tired.html

 

[Carl Fredrik Ahl]

4 hours ago, Strange said:

Do you have any evidence for this?

No, I just guessed.

 

5 hours ago, Strange said:

Or maybe the difficulty of dissipating heat means that the body's natural response is to slow down in oder to control body temperature - it makes us feel tired to stop us generating more heat.

Just found this, which confirms my latter guess: https://www.livescience.com/60116-why-heat-makes-you-feel-tired.html

Okay, but why doesn't you feel tired when your cold? Then the body also has to regulate the body temperature.

[Strange]

23 minutes ago, Carl Fredrik Ahl said:

Okay, but why doesn't you feel tired when your cold? Then the body also has to regulate the body temperature.

When you are cold, the body has to generate more heat, not less. So if anything you should feel more active so that you will warm yourself up.

[DrP]

18 minutes ago, Carl Fredrik Ahl said:

Okay, but why doesn't you feel tired when your cold? Then the body also has to regulate the body temperature.

At a guess... if you fell asleep when you were cold you might die of hyperthermia or something. All the shivering and energy burning probably keeps you awake...  the tiredness comes later when you are back in the warm.

[Prometheus]

Dehydration is probably a significant factor.

[Carl Fredrik Ahl]

16 hours ago, Strange said:

When you are cold, the body has to generate more heat, not less. So if anything you should feel more active so that you will warm yourself up.

But generating more heat means more energy being used.

16 hours ago, Prometheus said:

Dehydration is probably a significant factor.

Yeah, but even if you drink much water, you still can feel tired when it's hot right?

[Intrigued]

16 hours ago, Prometheus said:

Dehydration is probably a significant factor.

I'll drink to that!

[iNow]

Is this not a simple protection mechanism? I’m already too hot, and expending additional energy just makes me hotter? Better to rest until it cools a bit so as not to do organ damage or lose consciousness...