Solving a puzzle keeps your brain focused so you are never bored.
At night you have a lot of time to kill. That means you can finally finish the show your friends have already finished
When drinking water before bed, it can help you go to sleep
Though this may not improve sleep, it is nice to have late night eats. This is a nice recipe btw. ramen recipe
And if you can't do any of those, going back to bed is your last resort.