Seven tips for getting through a long flight

I have always deeply envied those people who can get on an airplane, buckle themselves into their seat and drop into a deep sleep that is broken only with the impact of the plane landing at their destination. How do they do that, I wonder, as I lie awake with the background noise of their gentle snores wafting around me. How can they possibly be so relaxed that they can nod off even before the seat-belt sign has been switched off? How is it possible that the noise of that wailing child or the hustle and bustle of the dinner/lunch service does not rouse them from their slumber?