Image of Professor Colin Espie
by Professor Colin Espie

The challenge for jet setters

If you travel across three or more timezones on a regular basis, the chances are that you're all too familiar with the effects of jet lag.

It can be hard to escape; former US President George W. Bush famously blamed jet lag when he repeatedly attempted to escape a Beijing press conference through a locked door. (Jet lag may have been to blame when he vomited on the Japanese Prime Minister and fainted on a state visit, but that's another story.)

We all have a built-in body clock, which is adapted for action during the day and rest at night, on a 24-hour cycle. Sudden changes in timezone mean that we behave out of sync with what our bodies expect. Jet lag is the result of the body's internal rhythms being out of step with environment. The obvious effects are being too alert at night and sleepy during the day, but they go much further…

• Irritability, headache, general misery

• Memory and concentration lapses, disorientation, unable to sleep

• Slow reaction time, tremors

• Hunger pangs or appetite loss, gurgling stomach or butterflies

• Diarrhea & vomiting, constipation

• Fatigue, muscle aches & pains, changes of temperature

• Getting up frequently during the night

As a rule of thumb, when you fly across more than five zones, it can take 4 to 6 days to naturally shift the body clock so that it is in sync with your new environment.

Even if you're not flying across timezones, early starts, late nights, sitting for long periods in cramped spaces, lack of exercise and night flights can all contribute to travel fatigue. The dry cabin air on long flights (5-15% humidity) can also cause mild dehydration, which can make jet lag worse.

Regular travellers have irregular daily routines which can make it hard for the body to wind down in readiness for sleep. Very early flights can also lead to broken sleep, as we anticipate the early morning alarm.

In this guide we cover some practical steps to help your body adapt more quickly, common questions, and a bit about the science of jet lag

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