5. Sitting upright, your body generates an adrenaline-like substance to keep blood flowing up to your brain. It keeps you from sleeping, and even if you do doze off, keeps you from having a deep restful sleep. We may not be able to afford the luxury flatbeds of first class, but make do with what you have and recline your seat as far back as you can.

By MSN Travel, 12/13/2010