Fasting during your long-hour journey can help you escape the grogginess that goes along with it, scientists have found.
Researchers from Harvard University found a so called a second "feeding clock" within the brain which keeps track of meal-times, rather than daytime. The mice studies showed that with fasting, this feeding clock overrides the master clock, and keeps the animals awake until they find food.

This way, by not eating, scientists suggest that shift workers and travellers could keep tiredness at bay.
The so called master clock, that is in charge with our daily sleep cycles, behaviour and metabolism, resides in an area of the brain known as the suprachiasmatic nucleus. This master clock is highly sensitive to daylight while, the new found so called “feeding” clock is sensitive to the eating patterns.

The researchers found that the "feeding clock" resides in an area of the hypothalamus known as the dorsomedial nucleus and that it could actually suppress the master clock and keep the mice awake and sharp until they ate again.

This feeding clock could be beneficial to travellers and shift workers to help them adapt to changes in time zones and night-time schedules and avoid feeling groggy and jet-lagged.

A trip from the US to Japan, makes one having to adjust to an 11-hour time difference. This takes a week, because the body's biological clock can only shift a small amount each day and then it’s already time to go home. Eating no food at all for about 16 hours would be enough for this new clock to take over.

So, avoiding food on the plane, or during a night shift and then eating after, should help you to adjust and avoid all the negative effects of the jetlag and working unsociable hours.