I saw a few people mentioned the racing thoughts keeping them up at night. This pretty much is the main reason why many people can't sleep. It has happened to myself since i was 10 years old, and girls, and a libido, and self consciousness came into my life. It is perfectly normal, and happens to us all.
I know for a fact that the better I myself feel, the easier it is to sleep. But, on those nights where i can't seem to sleep(which are becoming more and more rare, due to a few things + CBT), i slow down everything im thinking and stressing about. I then picture every bad situation that happened to me throughout the day. I re-picture the situations that are in my mind, but i picture them how i WANTED them to go. I recreate every bad thing that happened to me in a good fashion, how i wish it could have happened. Whether its an awkward convo, unfair person, confrontation, or even just staying in my room locked up for too long, i picture it how i wish the situation could have went.
This is just my thing i like to do, i am not saying it works for everyone. It really helps me to go to bed, thinking positively, and it helps to alleviate those negative emotions and feelings which don't do us any good to sleep with.
I got the strategy from The Secret Audio series. I recommend everyone on here give this a listen, very good series. Not that i take everything they say to heart, but at THE LEAST, it is very uplifting and motivational. I used to listen to it for a few weeks straight on my ipod when i ran every day. Enjoy everyone!