Sunshine to meal times: How to beat jet lag

Jet lag is what you feel when local time changes abruptly, but your body clock is playing catch up, says Dr Nina Rzechorzek, who leads research at the University of Cambridge on human brain temperature, sleep, and circadian rhythms.

"After rapid travel across several time zones, your internal biological time initially stays aligned with home while you are trying to sleep, eat, and function on destination time.

"That mismatch can cause disturbed sleep, daytime sleepiness, poor concentration, irritability, reduced performance, and digestive problems," she says.

And jet lag is closely linked to what are called our circadian rhythms – the body's internal body clock.

"Almost all the cells in our body maintain their own 24-hour clock, which are synchronised by a master clock in the brain," explains Dr Anna Edmondson, of the Laboratory of Molecular Biology in Cambridge.

"The master clock is set to environmental timing cues, one of the most important cues being daily cycles in sunlight and darkness. However, if the timing of the sunlight/darkness cycles suddenly change (you fly far east or west), then it takes several days for the master clock to adjust to the new time, leading to jet lag.

"So effectively, it's like your body is still stuck in the timezone of where you've just flown from."

Reporting from BBC News contributed to this story.