Typically, what often keeps most people awake is mind clutter. This, for me, is usually when I have a bunch of information floating back and forth that needs to be attended to and I don't want to forget so I run the same thing back and forth a million times keeping myself awake by doing so.
So, rather than do this, I learned to get up, turn on my computer, and write down everything cluttering my mind.This can take anywhere from 15 to 30 minutes, but, by writing it down, I can allow myself to sleep because I know I'm not going to forget something, which is what was keeping me awake.
Why not try it. What have you got to lose except sleep?
PS When your mind is uncluttered and you allow yourself to sleep you may need to set an alarm. :-)