I am at 30,000 feet in the air sitting in an airplane, a narrow metal tube 12 feet across. Fellow passengers ahead and behind me are sleeping because we boarded at 7:20 a.m., and like myself probably had awakened at 5:00 a.m. or earlier to be at the airport on time. However, unlike them and Jack Ryan, the protagonist of many Tom Clancy novels, I cannot sleep on an airplane. I suppose there are many reasons for this "failure," turbulence (the bane of Jack Ryan), noise, uncomfortable seats, anxiety or rumination of upcoming events, but am I better off for it?
In contemplating the answer to this question, I have decided to restrict my thoughts to flights within the continental United States with a maximum of three time zones to traverse although the principles generally apply if crossing more time zones. In traveling West to East, a phase delay is induced (i.e., one's body clock time will be earlier than the arrival time zone). Thus, it is unlikely that one will be sleepy at their usual bedtime. Sleep drive will be further diminished if napping occurs on the airplane. Additionally, if forced to awaken at their usual time in the arrival time zone, a traveler will tend to be sleepy. What about traveling East to West? In such cases, a phase advance is created (i.e., one's body clock will be later than the arrival time zone) and sleepiness will ensue at a time earlier than one's usual bedtime. There also will be a tendency to wake up very early in the morning.
Sleeping on the airplane should make it possible to stay up later in the new time zone by reducing sleep drive, but an early morning awakening may still be in the cards. Traveling North to South or vice versa will not cause any disruption in the synchrony of the body clock. Unfortunately, any napping on the airplane also will decrease sleep drive. This will make it more difficult to sleep at the new destination and compound any difficulties inherent with sleeping in a strange environment.
So let's go back to the original question. On one of those early morning flights, is it better not to sleep on the plane? Probably yes, and thinking about it may help to keep a person awake!