As a rule, carbohydrates make you sleepy; proteins and fats keep you awake. Bananas and milk are especially effective sleep-inducers.
Alcohol and caffeine If you're trying to sleep, neither alcohol nor caffeine help the cause. Avoid both.
Water Water helps the flier's cause in all cases. However, if you're trying to sleep, chugging a quart of water just before takeoff is going to require a mid-flight trip to the toilet. Moderation is the answer here; drink enough water to stay hydrated, but not so much that you're traipsing up and down the aisle of the plane all night. One of the best ways to overcome jet lag is to stay hydrated during your flight.
Layovers Eating is not advised, (see above) but you should drink plenty of water to stay hydrated. My approach is usually to brush my teeth, then head toward the gate, sit near a speaker or the agent, wrap my luggage handle around my wrist or ankle, and put my head back and try to sleep some more. You might ask a gate agent to make sure you don't sleep through the flight departure.
Skip the Movie Most movies won't put you to sleep, but rather keep you awake. Pass on the headphones, and close your eyes.
Sleep Aids An eye mask, inflatable neck pillow, ear plugs, and other devices can help the cause greatly. Don't worry about looking funny; bloodshot eyes at your morning meeting look much worse. If you can fall asleep without the use of pharmaceutical sleep aids, you'll be much better off upon your arrival, as drugs can cause lingering drowsiness or sluggishness that make it hard for your body to reset its internal clock. Gentle aids, such as the motion sickness treatment Dramamine, can dramatically assist you in falling asleep, however, if you have serious difficulties sleeping on planes.
When You Arrive Raise the window shade when the plane lands On an west to east flight, that first burst of light will have you blinking hard and miserably, but it will help mightily to reset your internal clock. The last few minutes of shuteye aren't worth stumbling off the plane into an unfamiliar airport before you wake up.
Reset your watch You need to start living by your new time zone. Reset your watch before you get off the plane. In fact, I prefer to reset my watch immediately after I board the last leg of my itinerary, as arrival times are always published in the destination time zone, and I know how long to my destination if I wake up and check the time. This can permit me to grab a few extra precious minutes of sleep.
Begin your day with familiar routines Rather than indulging your body's clock, live by your watch. If it's 7AM after an eastbound flight, have breakfast, coffee, whatever you usually do at 7AM. Grab a newspaper if you typically read one every morning. You probably won't feel hungry yet, and the coffee might not go down as smoothly, but soon enough you'll be glad you're on schedule. If it's 2AM after a westbound flight, head straight for your hotel or home and go to sleep.