system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why am I more active by night while I feel sleepy by day?

Passed 10 or maybe 11 pm, my thoughts get clear, I feel motivated to do even work I wouldn't normally feel like doing by day, and most of the times even my mood improves.
gpt
As humans develop, their sleep cycles shift later and later, making the best time for you to be awake also shift later and later. On a side note, though, sleeping all in one block is actually a recent phenomenon and not the natural sleeping pattern for humans.