Many travellers know the feeling of hitting a 3pm wall and wanting to go to bed, or waking at 3am with a racing mind and no chance of sleep. Jet lag, often described as the world's most annoying holiday souvenir, is the price of flying across the globe for work or leisure.
So how does it work, and what can you do about it?
What causes 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.
