insomnia
"For insomnia I think it helps, 1mg to 3mg depending on each one's body. But if you don't get to sleep properly, maybe anxiety is the cause. In my case and from my life experience, I do some tricks to beat both anxiety and insomnia:  1.5mg melatonin 30min before bed time; Spend those 30min reading a book (out of the bedroom) with just 5w blue-light; Take 75mg Trazodone when already in bed, just before program my alarm-clock, lights out; Always get up before 9am (no matter what); Exercise outdoors 40min (before lunch time ); Have 2 hobbys: listen to music (without headphones) and study collective sports; Dinner time before 8:30pm; And psychotherapy 2 times a month, forever. 
SO: melatonin is a part of a whole."