The primary cause of jet lag (or desynchronosis as it’s correctly known) is the disruption of our circadian rhythms based on the daily light–dark cycles we experience. However this is only the case when food is in plentiful supply, with new research suggesting that circadian rhythms based on food availability are able to override those of the light-dark cycle. This could offer us a simple and effective way of preventing jet lag: fasting for sixteen hours prior to your new time zone’s breakfast time.
I mentioned this in passing two years ago (just before undertaking a 25-hour Sydney to London flight), but after recently coming across the study again I felt compelled to point to it in more detail.
Researchers at Harvard Medical School and Beth Israel Deaconess Medical Center in Boston have now pinpointed a second [biological clock] that is set by the availability of food. […]
Clifford Saper, the senior author of the study, said this second clock probably takes over when food is scarce. It may have evolved to make sure mammals don’t go to sleep when they should be foraging for food to stay alive.
Dr. Saper says long-distance travellers can probably use this food clock to adjust rapidly to a new time zone.
“A period of fasting with no food at all for about 16 hours is enough to engage this new clock,” he said in a statement released with the study. Once you eat again, your internal clock will be reset as though it is the start of a new day […] and you should just flip into that new time zone in one day.