Jet lag is what happens to you when you fly to a new time zone. Some people get over it after a day of poor concentration and disturbed sleeping pattern but for some, it lasts more than a week. The more time zones you cross, the worse it can get. According to research, the travel direction is also a factor.
Why jet lag happens?
Understanding why jet lag happens is more complicated than your body adjusting to changing time zones. Internally, your body’s natural clock a.k.a circadian rhythm regulates the body to a 24-hour sleep cycle by syncing with external factors like sunlight. When you change time zones, this cycle is disrupted because the external factors no longer sync with the internal clock. Sunrise happens at a different time and meals happen at different times. Jet lag is the period where the clock synchronizes with the new external environment.
It is interesting to note that the brain cells from where the circadian rhythm is generated are not identical so their innate frequencies are different. Their combined average results in a sleep cycle for 24.5 hours, a little longer than a day. It is this half-an-hour different which makes the direction of travelling a factor in determining the severity of the jet lag.
When you fly west, the day on which you reach is longer than usual so you get extra daylight than normal. When travelling east, it is completely the opposite. You lose daylight and the Sun sets earlier than your body is used to. It is due to the longer sleep cycle of 24.5 hours that makes it easier to deal with the longer day and makes the jet lag worse on a shorter day. This phenomenon is termed as “East/West Jet Lag Asymmetry”.
Now that I think about it, I have experienced this before but didn’t think about it at the time. In 2013, I took a flight from New Delhi to Boston at 8:30 AM and reached at 7:30 PM ET. I was able to stay awake for a while, sleep at 10 PM and wake up at 6 AM. But going the other way, I took a flight at 10:40 PM and reached at 2:30 AM IST. I woke up in the afternoon and it took me a couple of days to adjust to the new time zone.
So what’s the point of telling you all this? After all, it’s not up to you, the flyer to decide the travel direction. How does little trivia help? There exists a diet called the Argonne diet which is specifically designed to ease the symptoms of a jet lag. It enables you to reset your circadian rhythm even before you fly so by the time you reach your destination, you are already adjusted to the new time zone.