Why do I feel exhausted and don’t want to do anything when the weather is hot?

I think it is because the temperature is high in summer. In order to dissipate heat, the body has rich blood circulation in the skin, so the blood supply to the brain is insufficient, making it easy to become unconscious and sleepy. There is also insufficient blood in the muscles, so the whole body is weak. On the other hand, muscle movement must produce heat. In order to keep the body temperature from being too high, a series of complex nerve adjustments will cause the muscles to relax and not produce heat, so the whole body is weak. Not only humans, but almost all animals are like this. You see, those lions in the animal world never hunt in the scorching sun. They all sleep under the shade of trees and wait until dusk to move around. This is all conducive to the self-preservation of life.