Ever Wondered Why Is Jet Lag Worse After You Have Travelled East? Here’s The Reason


Disturbed sleeping patterns, troubled digestive system, and perpetual exhaustion all point to one thing: the jet lag. Those who fly regularly have to face this menace more often.


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However, for the regular air travellers, the intriguing question is that why does our body requires longer to recover when we are flying east?

The neuronal oscillator cells regulating the circadian rhythm, an estimated 24-hour physiological processes cycle or the internal clock, fails to adjust to the new time zone fast enough, travelling which messes up our metabolism, sleeping pattern, and the overall functionality of our body for a few days after landing. Usually, the coordinated movement of these cells is stimulated by light exposure. However, as we travel, the pattern of this exposure is disturbed.


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The physicists from the University of Maryland have recently published their research featuring a mathematical model in Chaos, explaining the difference in the response of the brain cells according to the direction we are travelling in.

The Effect of the Circadian Rhythm on Jet-lag Recovery

A day of recovery per time zone travelled was used as a rule of thumb for jet lag recovery. That latest study reveals that the rule still holds true going towards the west. However, the pacemaker cells in the brain do not adhere to the 24-hour cycle. In fact, an extra half an hour clocked in by the circadian rhythm takes the cycle up to 24.5 hours.


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The lead researcher for this study, Michelle Girvan explained the working of the pacemaker cells using the racing cars on track analogy:

“Normally, the movement of the Sun acts as the “man with the yellow flag,” indicating where the circular track’s finish line is. This marker helps the pacemaker cells complete their circuit in correspondence with the environment. In the absence of a controlling influence, the clump of [pacemaker] cells completes the circuit within a period of time that may not correspond exactly to one day.”


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The circadian rhythm serves as an inbuilt clock that runs just a little longer than the 24 hours. Every day, the body tries to adjust to this cycle. While travelling towards the west, our day lengthens thus allowing more recovery time for the body to adjust to the innate cycle. But as we fly towards the east, our day is cut short, thus giving us lesser time to attune to our natural cycle. This is why it takes longer to recover from the jet lag as we travel towards the east.


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The research team also delved into the mystery of why some people recover faster from the jet lag? As Girvan puts it:

“Some people may have a natural circadian rhythm with a period of 24.5 hours, while others may have longer or shorter natural rhythms. Our model suggests that the difference between a person’s natural period and 24 hours controls how they experience jet lag.”


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The study reveals that for a westward trip, a person would require three to 3.5 days to recover from a journey across three time zones and up to 6 days to recover from jet lag if the trip took one through 6 time zones. On the other hand, those travelling towards the east would take four days to recover from a journey across three time zones while a trip crossing six time zones could take as long as eight days for recovery!

Those planning a trip to Australia, beware!


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