I am a teenager who sometimes, mostly before big tests or tennis matches, cannot sleep. Sometimes I think about the upcoming event and can't get it off my mind. I usually twist and turn to get into a "perfect" position (probably also causing me not being able to fall asleep). Also, I cannot sleep sometimes when I know I have to wake up early the next day. I even get nervous or frustrated because me not being able to sleep will effect my performance the next day! I can take tablets such as melatonin but I try not to. How should I approach going to sleep faster? Thanks!