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What causes jetlag?

jetlag blueball Crossing time zones
The primary cause of jetlag is crossing time zones. The more you cross, the worse will be your jet-lag, due to the disturbance of your body's inbuilt clock. Going east seems to be worse than going west. Flights that are more north-south or south-north won't disrupt your body-clock, but you're still likely to experience symptoms associated with jet-lag, caused by other aspects of long-haul flying discussed below. Children under three don't appear to suffer jetlag badly as they are more adaptive and less tied to a strict daily routine. Adults who adjust readily to changes of routine also seem less susceptible to jetlag than those who are slaves to a fixed daily timetable.

Your pre-flight condition
If you're over-tired, excited, stressed, nervous, or hung-over before the flight, you are setting yourself up for a worse dose of jet-lag. How many times have you heard travellers say "Don't worry, I'll catch up my lost sleep during the flight"? Well you don't really. The wise traveller who wants to get the most out of a trip has a good night's sleep prior to departure.

Dry Atmosphere
The air aboard passenger jet aircraft is dry. To people who normally live in more humid conditions the change can be a shock. In fact some sports teams wear special face-masks during long flights to prevent dehydration. The dryness can cause headaches, dry skin and dry nasal and throat membranes, creating the conditions for catching colds, coughs, sore throats or the flu. Drinking plenty of water helps, and some frequent flyers take a bottle of water with them. Coffee, tea, alcoholic drinks and fruit juices are not recommended. Water is what your body wants.

Cabin Pressure
At a cruising altitude of near 30,000ft the aircraft is pressurized to near 8,000ft. Unless you live near 8,000ft and are acclimatized to this pressure you may suffer from swelling, tiredness and lethargy.

Stale Air
Providing a constant supply of fresh air in the cabin costs the airlines money, and some are more willing to oblige than others. The air supply in business and first-class is often better than in economy class. A lack of good air tends to make you tired and irritable and can cause headaches. Sometimes if you ask the flight attendants to turn up the fresh air they will do so.

Alcohol
The impact of alcohol on the body is 2-3 times more potent when you're flying. One glass of wine in-flight has the effect of 2-3 glasses on the ground. Add this to the other problems mentioned here, and you can get off the plane with a hangover that simply compounds the effects of jet-lag.

Food and drink
Airline coffee and tea not only tend to taste awful - they often tend to be very strong and hard on the stomach, and orange juice has the same effect if you are not used to it. If you don't normally drink really strong coffee, tea or orange juice, don't over-do it while flying. Also go easy on the frequent meals served in-flight. You don't need them. And sitting in a cramped position puts extra pressure on your stomach. Also beware risky foods served on some airlines in certain parts of the world, including salads and cold meat and fish. According to the WHO, 50% of international travellers get stomach problems, so food care is important while flying.

Lack of exercise
Lack of limb movement due to sitting in a cramped position for hours is one of the worst aspects of long-haul flying. It's not only uncomfortable, but sets you up for a worse bout of jetlag afterwards. It has also been linked to potentially fatal blood clots (deep vein thrombosis or "economy class syndrome"). Do flexing exercises in your seat, especially for the legs, and if possible go for walks up and down the aisle. Take your shoes off and flex your feet. If you have a spare seat next to you, try to get your feet up. Get off the plane whenever possible at stopovers and walk around and do some exercises. If there is an opportunity during a ground stop, take a shower - it freshens you, tones the muscles and gets the blood moving again.

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