system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What stage of sleep are you in under anesthesia, and why does it feel like no time has passed?
gpt
Technically, you aren't sleeping. General anesthesia stops certain brain functions and places your brain into a state of true unconscious. This is why anesthesiologists are so important, because it's a very fine line between the amount needed to kncock someone out and the amount needed shut down too much brain function and kill them.

Interesting fact, unlike local anesthetics which paralyze the nerves to reduce or eliminate pain, general anesthesia doesn't stop your nerves from sensing or sending signal. Studies have been done that show that people's nerves fire like crazy during surgeries, but the general anesthesia prevents the brain from registering it.