Family doctor

Overview:

• Jet lag occurs after crossing more than three time zones
• Symptoms include insomnia, irritability, and altered bowel habits
• In general, flying on west-bound flights is easier on the body
• Get a good nights sleep before travelling
• Medical treatment involves the use of sleeping tablets, melatonin and stimulants
• New recommendations indicate jet lag can be treated with short spells of bright light

What is jet lag?

Jet lag is when the body's own time clock is out of sync with the country they are visiting.

Jet lag occurs when you fly over at least three time zones. There are 24 time zones around the world - one for each hour in the day.

In these cases a traveller cannot immediately adjust to the time zone of the country they are visiting. For example it may be 7am when you arrive but you will feel more like sleeping than having breakfast.

Symptoms of jet lag include insomnia, fatigue and altered bowel habits. Other problems include irritability, dehydration, problems concentrating and sometimes nausea.

Advice for minimising jet lag during air travel

Long flights can be hard on your body, but you can limit the undesirable affects of fatigue by taking the following advice:

• Travel from east to west when flying to and from Europe. You will spend more time in darkness, making it easier to sleep.
• In general, travelling north to south is least likely to give you jet lag because you may be able to stay in the same time zone. Otherwise, travelling west is considered best because you gain time in that direction - not lose it.
• If possible, make some adjustments to your body clock before you leave so it has less adjustments to make on arrival.
• Get a good sleep the night before you leave.
• Stop over in another country for two days during the trip if you are crossing more than six time zones.
• Drink plenty of water on the flight to avoid dehydration. Don't drink too much alcohol. And avoid coffee during the flight and on arrival.
• Avoid overeating, this may give you indigestion.
• Exercise your legs by taking a walk around the aircraft.
• Take short-acting sleeping tablets to avoid a hungover feeling when they wear off. An eye mask and earplugs may also help you sleep.
• Wear loose clothing for comfort. Your feet may swell during the flight so also wear lose fitting shoes or slippers.
• See your doctor if you get a heavy cold before you leave. Pressure on your ears during descent can be extremely painful.
• Airsickness is now unusual, but anti-airsickness tablets are available if you are worried about nausea.

Advice for adjusting to new time zones on arrival:

• Take a short nap on arrival and then go to bed at night.
• Try to keep the day on arrival free to rest if you are crossing more than six time zones.
• For the first three days do most of your activities in the morning if you have travelled from east to west, and in the afternoons if you have flown from west to east.
• Try not to use sleeping pills, but if you need to, use them only on the first two or three nights and them stop taking them so you do not get addicted.
• Taking a long-acting sleeping pill may be better for travellers following west-bound flights because of problems with early-morning waking after those flights.

Treatment for jet lag:

There is medication available to help minimise the symptoms of jet lag on arrival in a new country, but treatment depends on the level of alertness necessary on arrival.

People attending conferences or travelling for work may need more assistance with sleeping, than people travelling for recreational reasons.

There are three recognised treatments for jet lag. These include the use of sleeping pills (benzodiazapines), melatonin (a hormone which helps to adjust the body clock) and psychostimulants (to help keep awake).

A study in Switzerland of 300 travellers found 5mg of fast-release melatonin was the most effective method for using the hormone to reduce jet lag.

Another Swiss study compared melatonin with the benzodiazepine-receptor agonist Zolpidem, and found Zolpidem had the best effect on jet lag symptoms but had a higher rate of side effects than melatonin.

Melatonin alone used for several days after arrival was the second choice followed by a combination of melatonin and Zolpidem. (Zolpidem is not available in New Zealand. The closet choice would be temazepam).

A study published in the British Medical Journal in 1989 found that melatonin could help restore normal sleeping patterns in weary travallers. The study of 20 people travelling to and from New Zealand and Britain found those taking 5mgs of melatonin before, during and after the flights, returned to normal sleeping habits in just under three days compared to more than four days for those without treatment.

However, there is controversy over the long-term use of melatonin because there have been no studies to prove its safety.

While melatonin is available without a prescription in many overseas countries, in New Zealand it is a prescription-only medicine.

Another new treatment being advocated to help reduce jet lag is light therapy. This means 30 minutes of bright sunlight or a bright light to help the body adjust to new time zones. The light should also be taken at different times, depending on the length of the flight and the direction you are travelling in. The following guidelines apply:

• If you travelled on an east-bound flight over up to six time zones, light in the morning is advised.
• If you travelled on a west-bound flight over up to six time zones, light in the late afternoon is advised.
• If you travelled across 10 to six time zones on an east-bound flight you should avoid light in the morning and seek light at noon.
• If you travelled across 10 to six time zones on a west-bound flight, avoid afternoon light and get light at midday.

Without treatment with melatonin or light, it is believed travellers adjust at about the rate of one time zone each day. But using a combination of both methods can increase the rate of adjustment to up to three time zones a day.