Jet lag (or "jet-lag") is a physical condition caused by crossing multiple time zones during flight. The condition is generally believed to be the result of disruption to the circadian rhythms (i.e. the "light/dark" cycle) of the body. It can also be exacerbated by experiencing sudden changes in climate or seasonal conditions, as well as the low humidity commonly experienced in the cabin of an aircraft.
Fatigue
Being worn out and tired for days after arriving, generally accompanied by a lack of concentration and motivation, especially for any activity that requires effort or skill, such as driving, reading or discussing a business deal. But even simple daily activities can become harder, and one's capacity to truly enjoy a tourist holiday is significantly reduced.
Disorientation, fuzziness
Having to return to check three times to see if a hotel room was left locked or unlocked is a typical symptom reported by flight crews experiencing jet-lag. Again, not good if you're on a business trip.
Becoming irrational or unreasonable
"Losing it" is another symptom reported by aircrew, which explains why long-haul flights get very tedious near the end, and why going through customs and immigration and getting to the hotel often seems like a real drama.
Broken sleep after arrival
Crossing time zones can cause you to wake during the night and then want to fall asleep during the day at your new location. Your inbuilt circadian rhythms have been disturbed, and it can take days for the body to readjust. NASA estimates you need one day for every time zone crossed to regain normal rhythm and energy levels. So a 5-hour time difference means you may require five days to get back to normal! Can you afford that?
Dehydration
This can cause headaches, dry skin and nasal irritation, and make you more susceptible to any colds, coughs, sore throats and flu that are floating round in the aircraft.
Discomfort of legs and feet
Limbs swelling while flying can be extremely uncomfortable, and in some cases may prevent travellers wearing their normal shoes for up to 24 hours after arrival.
What causes Jet Lag?
Crossing time zones
The primary cause of jet-lag 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 jet-lag 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 jet-lag 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.
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 jet-lag 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.
Who Gets Jet Lag?
Almost everyone on a long flight suffers jet-lag to some degree.
Studies by Upjohn and Condé Nast have shown 93-94% of long-haul travellers experience it, and a New Zealand study showed a similar proportion of flight attendants on international flights suffer from its effects despite being accustomed to long-haul travel.
Passengers
It affects passengers even more than the flight professionals, firstly because they are generally less accustomed to the factors causing jet-lag, and secondly because they are confined to a cramped space for long periods. There are also other factors such as the lack of fresh air in passenger areas.
Not all people to the same degree
Young children often seem immune. People who normally stick to a rigid daily routine or are bothered by changes of routine, are often the worst sufferers. People whose normal lives involve highly varied routines can often adjust their circadian rhythms better and adapt to a disruption of normal eating and sleeping patterns. People who get to sleep easily may also cope better with the adjustment.
People crossing multiple time zones
The length of the flight is not the critical issue. The most important single factor is how many time zones you cross. People can suffer jet-lag just crossing the United States from New York to Los Angeles (three hours' time change) but would be much less affected by flying from New York to Bogota in Colombia, a north-south flight of even longer duration. But there are also other factors besides crossing time zones that contribute to jet-lag, and these may be experienced even on north-south flights.
People in poor pre-flight condition
If you are not fit, rested and healthy you will probably suffer more jet-lag than others on the same flight. Stress and loss of sleep before your trip will make it worse. Pre-flight partying and over-consumption of alcohol will do the same.
Techniques for reducing Jet Lag: Jet-lag is caused by a whole range of factors involved in longhaul air travel, and there are a number of practical ways in which you can reduce its effects. These include some simple steps to make your flight more pleasurable and your recovery faster.
Pre-flight
This is a key aspect of combating jet-lag. Before departing, make sure you have all your affairs, business and personal, in order - and don't leave it all till the last moment. Ensure you are not stressed-out with excitement or worry, or tired or hung-over from a function the night before. A trip is so much more enjoyable if you feel "everything is under control". Get a good night's sleep just prior to departure, and get plenty of exercise in the days before. Try to avoid sickness such as flu or colds. If you have a cold, flying will probably make it worse - ideally you should delay the trip.
Night or day flight?
This is largely a matter of personal preference, but most travellers think daytime flights cause less jet-lag because you get a night's sleep on the ground at either end. You may "lose" a day by spending it on a plane, but weigh this against the loss of quality time at your destination if you feel fatigued for the first day or two due to sleep-loss.
East or west?
Whether it is better to fly eastwards or westwards is the subject of debate among frequent travellers, but there is some evidence that flying westwards causes less jet-lag. This is probably because the crossing of time zones occurs more gradually and is easier to adjust to.
Drinking fluids
The dry air in aircraft causes dehydration. Drinking plenty of non-alcoholic fluids counters this. Water is better than coffee, tea and fruit juices. Alcohol not only is useless in combating dehydration, but has a markedly greater intoxicating effect when drunk in the rarefied atmosphere of an airliner than at ground level.
Sleeping aids
Blindfolds, ear plugs, neckrests and blow-up pillows are all useful in helping you get quality sleep while flying. Kick your shoes off to ease pressure on the feet (some airlines provide soft sock-like slippers, and many experienced travellers carry their own).
Noise reducing headphones
Some long-haul air passengers find they sleep better in-flight with these headphones which reduce the effect of engine noise, not just by shutting it out but by emitting a signal that cancels it out. They work best once the aircraft is at cruising altitude and the engine noise is constant. Some airlines provide them in business and first class, and they're available for purchase at a price.
Exercise
Get as much exercise as you can. Walking up and down the aisle, standing for spells, and doing small twisting and stretching exercises in your seat all help to reduce discomfort, especially swelling of legs and feet. Get off the plane if possible at stopovers, take a walk and if possible do some exercise (this also helps to reduce the risk of blood clots).
Showers
During extended stopovers on a long-haul flight, showers are sometimes available. A shower not only freshens you up but gets the muscles and circulation going again and makes you feel much better for the rest of the flight. Trans-Pacific pilots have told us taking a shower in Hawaii helps them recover more quickly from the general effects of jet-lag after the flight.
