Food-Based Body Clock the Key to Jet Lag

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.