Look through your habits:
Room temperature should be around 19 degrees or a little bit lower. Too hot is not good.
If you dont get into asleep, DO NOT stay in the bed more than one hour. Get up and do something else, better easy, monoton but requires concentration but not exciting. Like sewing, reading of a boring book... Get a warm bath.
DO NOT sleep during daytime.
Avoid tea, koffee.
Good habits are more reliable than pills, especially those effective ones who people easily get addicted to. Melantonin doesnt work if you dont lack of it.
A bit unsual that you mentioned that you lose much weight. Are you anxious during the day as well?
Sorry for the spelling. My English is not good.