Just don't use the computer at night and turn down the brightness. Also if you are in a dark bedroom, and you are looking at your bright screen even after it has been toned down to the minimum, turn on a light that could illuminate your room!
In my experience, it doesn't really. I stay up till 12-1 staring at a screen, and I can fall asleep in... idk, but then again, I've been doing this for a few years, so I don't know how long it would take me if I didn't do this.
Same here, except I can't fall asleep until midnight to 2AM when I don't stay up late. Thus I wake up at around noon most days. (Today's an exception because I woke up about three hours ago, then got up an hours ago.