system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When you pass out after they give you general anesthesia for surgery, why does it feel like you've only been passed out for a few seconds when it's been way longer?

This has happened to me also when I used to use heroin, didn't even know you OD'd until you wake up with the paramedics, it's like instant.
gpt
Most anethesia doesn't cause "sleep" it causes uncouciousness. This why too much will kill you. It would take more to OD on melatonin (which doesn't even cause sleepiness, just enables sleepiness, if everything else aligns). Anesthesia interrupts concious thought and stops it, interrupting your ability to keep track of time/logic/what-have-you.