[nijaru]

Growing up somewhere with a Mediterranean climate that has hot summers, I’ve always assumed it was to sleep through the heat before a/c was invented.

[taeric]

There is almost certainly something to this. Sun exposure is dangerous.

[nradov]

How can people sleep during the hottest part of the day? I've never been able to manage that.

[eru]

You can doze off. And falling asleep is a skill you can train.

(I can nap in hotter and brighter conditions during the day than I can tolerate at night.)