Say no to drugs!
Jetlag is a pain in the butt if you have a busy schedule, but the alcohol and drug method of making yourself sleep isn't really advisable and can replace jetlag with conditions much more serious...
Try and avoid medicating yourself too heavily on long-haul flights, the risk of blood clots increases quite dramatically with the use of heavy sedatives - even when you're asleep small muscle twitches move the blood around your muscles enough to prevent clotting, sleeping pills suppress certain states of sleep and prevent that happening. You need to be in a state where you can move about every so often, not comatose for 8 hours!