system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does dying or falling in a dream cause you to suddenly wake up, no matter how deep of a sleep you are in?
gpt
When your brain is telling you that you are in mortal danger (falling from a great height, about to be hit by a large object, etc.) your brain releases adrenaline, which is the all-purpose contingency plan for dealing with danger. That rush of adrenaline effectively prevents you from sleeping, and wakes you right up.