Sleeping on a plane: why it's so hard and what it involves

Cabin air and reduced pressure

Cabin air, with relative humidity often between 10% and 20%, dries out the respiratory tract and disrupts the relaxation necessary for falling asleep. The reduced pressure, equivalent to about two thousand meters of altitude (on newer models with composite fuselages it drops to about 1,800 meters), slightly reduces blood oxygenation and makes sleep less deep.

Circadian misalignment and constant noise

The body receives light and activity signals often at odds with its usual biological clock, especially on night flights with meals or cabin service. The constant noise of the engines, though less disturbing than sudden sounds, keeps the brain nonetheless in a state of partial alert that hinders the deeper phases of sleep.

What it means for recovery

Fragmented sleep on a flight leaves a residual sense of tiredness even after several hours of apparent rest, because deep sleep phases are mostly lacking. Understanding this physiological limit helps not to count on sleep equivalent to that of one's own bed, orienting expectations toward partial but realistic recovery.

It's better to aim for a short, targeted nap in the middle portion of the flight, during the hours when cabin service is finished, rather than hope to sleep for the entire journey.