Chronotype and Jet Lag: Why Some People Recover Faster Than Others

Two people take the exact same overnight flight from Rome to New York. One is functional and cheerful by the second day; the other is still fighting fatigue on day four. Flight duration, cabin conditions, and time zones crossed were identical. The difference often comes down to chronotype — your individual, genetically influenced tendency toward being a morning person or an evening person.

Chronotype isn't a personality trait or a matter of discipline — it's a measurable biological characteristic, largely driven by variations in circadian clock genes (such as PER3) and the natural length of your internal circadian period. Researchers typically place people on a spectrum from strong "morning types" (larks) to strong "evening types" (owls). Most people fall somewhere in between.

Validated tools like the Morningness-Eveningness Questionnaire (MEQ) or the Munich Chronotype Questionnaire (MCTQ) are used in sleep research to classify chronotype, and both are available online if you want to identify your own tendency.

Evening types generally have a naturally longer circadian period, which makes it biologically easier for them to delay their clock (useful for westward travel) and harder to advance it (a problem for eastward travel). Morning types tend to show the opposite pattern — they often adjust to eastward travel a little more easily but can struggle more with westward shifts.

Chronotype is one more piece of the individual variation that general jet lag advice can't fully capture — which is exactly why cookie-cutter recovery plans work better for some people than others.