One thing that's always helped me get my sleep schedule on track was staying up for a few days. I've had insomnia pretty much my entire life, being wide awake at night but sleeping for most of the day. It was made even worse when I started working overnights. When I had to switch back to days I didn't sleep for about 2 days to get my body exhausted. Usually I'm wide awake until 3-4am then wake up around 2 or 3 in the afternoon but after having stayed up for a few days I was able to fall asleep by 10pm and stay asleep until the next morning. It's important to get out of bed as soon as you wake up because the more sleep you get in the morning the less tired you'll be later that night. There really isn't anything you can do when it comes to shutting your thoughts off to my knowledge since you're always going to be thinking about SOMETHING, however you can change what your thoughts are about. Listening to some soft music or one of those relaxation audio books with headphones on usually helps put me to sleep. A lot of those audio books have some sort of participation such as performing deep breathing exercises which will help you focus on that instead of whatever is bothering you.