I have to take 5mg of melatonin to help me fall asleep?

Insomnia: Yes, you can try to take it. It may or may not help, though.

Sleep: It isn't certain which dose of melatonin would be right for you. Some people might start at 1 mg or 3 mg initially to see what dose works. Also use good sleep hygiene. 1. Keep a regular bedtime & wakening time (to include weekends). Get up the same time each day, regardless of what time you fell asleep. 2. Make a regular, relaxing bedtime routine. Relaxing rituals prior to bedtime may include >>.