Well yes, sleeping is a good way to prevent boredom, also, id rather sleep than looking at a wall

I would either do like Pugsa said and play the 500 games on my Craptop or fire up my Xbox 360 or you know DO SOMETHING OUTSIDE. lol

crazy thing is..my reading habit took the most of my time rather than my internet time
so i can be like not noticing that i don't have wifi for 1-3 days or a week perhaps

I've been in a situation Б3 months without internet
spent all of my boring days locked in my room just watching tv, listen to some shitty musics, and reading some novels

Hang out with some friends man. You'll soon realize it's much better than hanging out on the computer doing nothing. I'm in too deep though. Even if you just hang out with some friends to just play games or browse the internet, it's beats doing it by yourself.

Make singleplayer replays
Offline stuff with paint/gimp/photoshop
watch tv
read books
go outside
build something (if you have the resources to do so)
Download anime/something else you enjoy watching
Anything works really

When I have no internet my entire life improves immensely.
I become more productive, more social, healthier and happier as consequence.

It's basically a drug.

Last time we changed ISPs (5 or so years back), my grades noticably rose by around two levels (C/D to A/B), I got together with my (not current) girlfriend and I picked up coding as a hobby.

Then the net came back and I went back to playing league all day.

i just go make replays on toribash or do some art stuff,as video or texture making.
rarely i go out of home,but i can do it.
or i study reading books that i havent read.

In the past I've been downloading huge chunks of manga in public places to read where I lack WiFi. Otherwise I like to record improvisations and turn them into sound doodles. I don't need WiFi for composition either. I have 4 instruments I want to get better at, so practice is always a thing. The list of books I should read is enormous and there are games I want to finish.
Creating/playing music is really entertaining, I'd recommend it.

I posted here a few days ago and forgot to mention the best of the things I do when the WiFi is down. Play with my dog. I play with her even with the WiFi on because it's fun and she needs her exercise, but having no access to the internet gives me more time to spend with her. It's fun and shit... yeah.