The idea of flying through multiple time zones might excite someone who has never done much travelling, but for the seasoned traveller who has suffered from jet lag, it can be a daunting feeling. Some people suffer from jet lag more than most, and it can take as long as a week for some of them to recover.
The two factors that seem to have most impact are:
- The number of time zones you fly through, and
- The direction in which you fly.
Looking at a map of the world with time zones indicated on it, you will see that Greenwich Mean Time is in the middle. This is the time at the Royal Observatory in Greenwich, London. When we refer to it as a time zone, we normally call it "co-ordinated universal time". In the United Kingdom, Greenwich Mean Time is the official time during the winter months. But because of daylight saving, when time is officially set back an hour so that the light hours in the day are longer, the country uses what they call "British summer time".
On the left of where Greenwich Mean Time is you will see 12 vertical strips each indicating a time zone that is progressively one hour behind the UK (-1 to -12). On the right you will see another 12 vertical strips, but these are ahead of the UK (+1 to +12). The actual width of each strip is approximately 1,000 miles or 1,600 kilometres. Each of these time zones has its own name including the Pacific Zone in the USA.
What this shows simplistically is that every place in each individual strip is within the same time zone. When it comes to travelling, if the aeroplane stays in one time zone, when you get to your destination, the time that has moved on will coincide with however many hours you were up in the air. But if the plane travels through different time zones, you will either lose or gain time, depending on the direction you are travelling in.
To illustrate, assume you are going to fly from Sydney to London. There is 10 hours difference between the two cities, which means that you are going to travel through 10 time zones. When you leave Sydney it is 6 pm, and because London is behind Sydney in time, it is only 8 am there. You get to London at about 6.30 am the next morning, when it is already 4.30 pm in Sydney. This means that you have gained 10 hours. So you still have an extra 10 hours to cope with before you get to 4.30 pm.
You may understand this with your head, but your body's internal clock can be forgiven for becoming very confused.
Of course the opposite will happen if you fly back to Sydney, and you will lose ten hours.
Generally travellers who have suffered from jet lag say that it is much worse when they travel eastwards (in this instance from London back to Sydney). Somehow it seems to be easier gaining time than losing it.
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