system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does a human being stay in a coma for many (like 10 or 20) years, and what wakes them up?
gpt
While you are in a coma, assuming that you are being kept alive and your brain has some function, your brain devotes a grear amount of enery to repairing itself. This process is difficult and energy intensive so some times it takes many years for the brain to repair itself to a level were you can remain conscious.