system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why does sitting out in the sun all day make you so tired even if you’re not doing any physical activity?
gpt
your body is finely tuned to a certain temperature. the hotter or colder the outside temperature is the harder it works to get back to what it wants. your internal body is working hard pulling levers and turning valves even if youre just laying down flat in the sun all day long.