moderate reduction in oxygen levels for a short period accelerates the adaptation of the body's clock to different time zones to help adapt to jet lag

Both light exposure and feeding time are well-known regulators of the circadian clock. Oxygen appears to function as a resetting cue for circadian clocks. Interestingly, the majority of modern commuter airplanes have a cabin oxygen pressure corresponds to ∼16% O2, which may actually aid in jet lag recovery.