Take melatonin and valerian root at bedtime. If you wake up at 3am, take another melatonin. You can get these supplements over the counter at any drug store, supermarket, WalMart, etc. They're very common and easy to find.
Melatonin is a natural substance produced by the body. The good thing is that if you need to be awake quickly in an emergency, you can do so. It won't affect your ability to get up in the morning even if you take it at 3am.
Valerian root is a mild... not sure of the right word... google it, I'm too lazy. Anyway, it is widely used to help people get to sleep. I've never felt groggy after taking it. You could try taking it as well at 3am and see how you feel. It doesn't seem to have any negative effects on me, but YMMV.
I also have a prescription for Ambien. When I'm traveling and absolutely must go to sleep early to get up at 4am or whatever, I'll take a half tablet. Thirty 30 tablets lasts me about two years. I would NOT recommend Ambien for regular use. It makes users groggy. It's almost like being drunk. A flight attendant tells me stories of passengers who take this and they can't wake them up when the flight arrives.