I don't sleep very well and am frequently awake in the early hours. I find if I just lay there, my mind starts to race with anxiety so what tends to work for me is I either read a book concentrating really hard on the words so my brain can't think of anything else or I play music really loud on my headphones which again, tends to block out unwelcome thoughts.
If I think there's a chance I might fall asleep again deep breathing helps, make it noisy so you can hear it and concentrate on it.
Don't put yourself under pressure to go back to sleep, as that only makes the anxiety worse.