Anecdotally (for me at least), flying west always feels easier than flying east. For instance, if you leave Los Angeles around noon and land in New York around nine, you can be hard-pressed to get to a restaurant in time for dinner. Meanwhile, if you depart JFK at noon, sometime you’ll arrive at LAX practically in time for a second lunch. But a new study suggests our stomachs aren’t the only biological element behind this flying east versus flying west phenomenon. Turns out it might be easier to recover from jet lag when you fly west because of an odd feature in our circadian rhythms.
A team of researchers from the University of Maryland published a study in the journal Chaos today entitled, “Resynchronization of circadian oscillators and the east-west asymmetry of jet-lag.” Despite the unwieldy title the concept is relatively simple: The “neuronal oscillator cells” in our bodies that regulate our circadian rhythms don’t actually follow a 24-hour cycle; they tend to follow a slightly longer 24.5-hour cycle. Knowing the difference in these two cycles, scientists were able to run mathematical models to better understand jet lag recovery after travel through different amounts of time zones in different directions.
Turns out that small half-hour difference can have a big effect on recovery time when flying. According to Live Science, when heading westbound, three time zones can be adjusted to in less than four days, six time zones can be adjusted to in six days, and nine times zones can be adjusted to in eight days. But when heading eastbound, three time zones requires longer than four days to recover from, six time zones takes a whopping eight days, and nine time zones can leave flyers needing over twelve days to get fully back to normal.
However, the researchers stress no set pattern exists for every person. “Some people may have a natural circadian rhythm with a period of 24.5 hours, while others may have longer or shorter natural rhythms,” Michelle Girvan, an associate professor of physics, told Phys.org. “Our model suggests that the difference between a person's natural period and 24 hours controls how they experience jet lag.”
To summarize, if you’re a weirdo with a screwed up circadian rhythm, only fly west. Or maybe just stick to driving. At least I think that’s the takeaway. That study title really is super confusing.