The world is divided into 24 time zones, and jet lag occurs when you cross over a number of time zones at once. Most passengers experience some form of jet lag after trips of more than four hours either east or west. Travelling in a westward direction is more body-clock friendly than flying in an eastward direction. So, your body adapts better when travelling west because you are extending your day, rather than travelling east, when you are shortening it. In other words, it is easier to delay sleep for a few hours than force yourself to sleep when you are not ready. Symptoms of jet lag include insomnia, irritability, and altered bowel habits.
As well as the disruption of the body's circulation rhythms, more commonly known as our 24-hour clock, a major contributory factor to jet lag is the lack of oxygen in the pressurized cabin, which causes dehydration and salt depletion.
In order to reduce the effects of jet lag, here are some simple tips which may help:
- A couple of days before you travel try going to bed earlier if you are travelling east and later if you are travelling westbound.
- Avoid heavy meals immediately before travelling. The lower air pressure in the cabin can mean you get bloated more easily, leading to discomfort. Avoid typically “gassy” foods for the same reason.
- Immediately on take-off, change your watch to the local time of your destination, so that you become accustomed to your new time several hours before arrival.
- Get as much exercise on the flight as you can by walking up and down the aisles. If you have a choice, it is probably better to choose an aisle seat so that you don’t disturb your neighbour every time you get up to go for a walk. Use any refuelling stops to take longer walks.
- Drink plenty of water during the flight. The dry air inside an aircraft not only causes dehydration, but also causes passengers to sweat profusely (this isn’t noticed because the sweat dries immediately). One simple remedy is to add a rehydrating sachet (such as Dioralyte) to your water every four hours or so to replace lost salt and minerals. Take another dose on arrival.
- Avoid drinking coffee and tea during a flight. They can cause extra dehydration because they are diuretics.
- If you have a stopover on long-haul flights, take a shower if possible. The water boosts circulation and helps get your muscles going.
- Try to adjust your mealtimes and bedtime to local times immediately on arrival.
- Melatonin is a hormone produced by the human body during darkness and broken down in daylight. Its function is to synchronize the body's activities with the 24-hour rhythm of the day; it makes you sleepy in the dark and lets you wake in daylight. A dose of melatonin tablets, taken at the right time, is supposed to "reset" your body's clock. In the UK it is only available on prescription, although it can be bought over the counter in the US and many other countries around the world. If you are considering melatonin tablets, make sure you find as much information as possible beforehand. Some studies have shown that miscalculating when you should take the tablets can lead to even worse jet lag.
Updated June 2008
