I use Valium (generic: diazepam) before a flight I want to sleep on. It's a mild sedative, and you can get either 2mg, 5mg, or 10mg pills from your doctor. I'm a big guy so I take the 10mg pill and it puts me to sleep for a couple of hours. (Note: I am not a drinker, and my stomach is typically empty when I pop a Valium before a flight.) Please ensure you do not have an addictive personality before you sign-up for Valium, however, as it is a narcotic and is easy to get hooked on. I do not have an addictive personality, and a bottle of 30 pills can last me an entire year.