system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does putting someone in an induced coma prevent further brain damage?

When someone suffers a serious head injury, they can be put into an induced coma to reduce the chance of further brain damage. How is someone put into an induced coma, and how does being in an induced coma prevent further brain damage?
gpt
They generally don't just put you in a coma then say "good enough!" and walk away, they generally put you in a coma so they can do a thing to you that you'd not put up with if you were awake, like they cut part of your skull off and leave your head open or they cool your brain way down to stop swelling. 

if your brain is sitting open or has fluids pumping in and out to cool it they basically need you to absolutely not move around for a couple days and do not want you awake ever till they put you back together.