system
Given the following post, respond as if you're commenting on Reddit:
human
What is the most basic form of life that still displays sleep-like behavior?
gpt
It seems to be the tiny roundworm C. elegans, not coincidentally one of the most intensely studied basic forms of life. It does something sleep-like called lethargus before each time it molts. This tends to suggest that sleep goes way back in our evolutionary history, for whatever reason.