I struggled a lot with sleep when I was working weird hours / nights. Even though I couldn't have a proper routine with work and things, I found it helpful to have a routine I'd go through before going to bed. Avoiding TV & computer before trying to sleep. Sleep mask and ear plugs are really helpful if you're trying to sleep during the day!

If it's mainly upsetting thoughts that are keeping you awake, what about trying meditation or something like a progressive relaxation exercise? There are some good guided ones that you can download, and I find that doing something like that can help me relax enough to sleep, or at least get some rest, and takes the focus off anything I'm worrying about.

I hope you manage to get some better sleep soon