Yea this is a problem. There are some techniques like auto-suggestion. I heard about one to fall asleep and it's very effective one. You start with your mind at thumbs and let them dissolve into the air and slowly continue higher over legs. Then hands, stomach, chest, neck, head. Just feel like those parts are becoming nothing but air. Like your body is disappearing.
There is also a sister technique. You visualize the same but instead of lightness you feel heaviness. Like those parts of your body are extremely heavy.
Try also to go to bed and leave everything behind. Just clear your mind before going to sleep. Feel relaxed. You should not take your problems to bed.