A problem faced by many travelers, regardless of how far they travel, or whether or not they’re traveling through a time zone, is that they sleep fairly well the first night of their trip but see a marked decline in sleep quality on night two and thereafter. It follows that by day five or six, sleep quality peaks, and sleep of a typical person returns to normal around day 10. This effect is seen in time changes as low as three hours but is augmented when traveling further distances.
But is this common problem influenced by the direction of travel? This was a question that the Sleep Cycle researchers have been investigating. The key finding from the new report was that traveling eastwards from the U.S. or Canada (that is going forward in time) is far worse for getting good quality sleep compared with traveling west (which is moving backwards in time). Overall, the data suggests that westbound travelers tend to experience better sleep than when they are at home.
Furthermore, the findings suggest that during the first five days of travel, people experience less severe jet lag when they travel west. This is not only comparable to eastbound travelers it also relates to many people who travel without moving through any time zones. This effect seems to be greater the further west a person travels.
In support of such findings, scientists have reported to the journal Chaos (“Resynchronization of circadian oscillators and the east-west asymmetry of jet-lag”), a mathematical model of the oscillations of the brain’s pacemaker cells which seeks to explain why eastward jet lag is worse than the westward kind. This seems to occur as cells respond differently to the time change and in the way that they acting upon each other, in relation to the direction of travel.
A further reason relates to circadian rhythms. The body clock is tuned such that a person will experience a surge of energy in the evening, which means that, say a Miami-to-Paris traveler, gets ‘a second wind’ just before Parisian bedtime, making it much harder to wind down and catch some good quality sleep.
