I used to take 10mg of melatonin plus valerian root for sleep. It was a good combo. It helped me a lot. I went off of it at the beginning of the summer because I’ve read that if you take it longer than a few months your brain stops producing its own melatonin and then you become dependent on it. I didn’t have any problems going off of it though so I don’t know how true that is. I took it for at least a year if not more. Now I just take it if I have trouble sleeping. I’d say it takes about an hour to work.