system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: How come I can get really tired reading a book or watching tv, but when I try to go to sleep immediately after I toss and turn for hours before finally falling asleep?
gpt
If you're like me, it's because your mind races. Reading or watching TV means something is effectively doing a lot of the "thinking" for you. You can start to doze and still have the thoughts be fed to you. When thinking in bed, some thoughts lead to more and it just spirals out of control. 

Funny thing is, when you're in bed and can't sleep and your mom texts you to take out the trash. Sleeping is almost instantaneous.