What Is Jet Lag? What Causes Jet Lag? How Do You Prevent Jet Lag?

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Main Category: Sleep / Sleep Disorders / Insomnia
Also Included In: Neurology / Neuroscience;  Endocrinology;  Psychology / Psychiatry
Article Date: 26 Sep 2009 - 0:00 PDT

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Jet lag is also known as time zone change syndrome or desynchronosis. It is considered a sleep disorder that can affect everybody who travels across multiple time zones in airplanes.

Jet lag effects largely reflect de-synchronization between the body's internal time clock and local environmental cues.

Our internal clock - also called circadian rhythm - which tells our body when it's time to be awake and when it's time to be asleep, is disrupted by jet lag. The more time zones crossed, the more likely we are to experience jet lag. It happens because our body finds it complicated to change to a new time zone. Jet lag can disturb the sleep pattern, leaving us feeling sluggish with fatigue and low-energy causing difficulties staying alert.

Researchers from the University of Washington revealed that the disruption occurs in two separate but linked groups of neurons in a structure called the suprachiasmatic nucleus, below the hypothalamus at the base of the brain. One group is synchronized with deep sleep that results from physical fatigue and the other controls the dream state of rapid eye movement, or REM, sleep

According to Medilexicon's medical dictionary, jet lag is " An imbalance of the normal circadian rhythm resulting from subsonic or supersonic travel through a varied number of time zones and leading to fatigue, irritability, and various functional disturbances."

Who gets jet lag?

Anybody can suffer from jet lag, regardless of how frequent the person travels by plane. Frequency of travel does not reduce jet lag. People of any age can build up this condition. However, it is more common in individuals over 50 years of age, and is relatively rare in children and babies.

Jet lag may be a burden for people who have to fly frequently or who are travelling to important meetings or events. It is proven that it does not cause any severe or long-term health problems. All symptoms of jet lag disappear within a few days.

What are the causes of jet lag?

The globe is separated into 24 time zones, with The Greenwich Meridian (GMT - Greenwich Mean Time) is the base. It is an imaginary line that passes through Greenwich, in London, and is used to measure longitude. The time changes by one hour for every 15 degrees travelled in either direction from the Greenwich meridian.

Jet lag is caused when the traveler crosses quickly over a number of time zones. This alters the body's normal "circadian rhythm", or "biological clock" which controls the body's 24 hour schedule of when it needs to sleep and when it needs to be alert or awake. Because we can travel so quickly in an airplane, the body has to try to catch up, and re-establish its circadian rhythm. It takes time for humans to adjust to new times of light, darkness, eating, and even temperatures.

Studies also suggest that the oxygen levels in an airplane cabin could also play a role in jet lag. Because air pressure is relatively low in the airplane cabin, the amount of oxygen in the blood is reduced. A decrease in the quantity of oxygen can have an effect on physical and mental abilities, making us more sluggish, exhausted, and lacking in energy. People with conditions, such as heart or lung disease, or even anemia which is when the red blood cells are not able to carry enough oxygen, may be more severely affected by lower blood-oxygen levels.

• Travelling East and West - the symptoms of jet lag are usually more obvious when someone travels east, rather than west. This is because the body finds it easier to adapt to a somewhat longer day (in the west) than a slightly shorter one (in the east). The condition is not associated to the distance of the flight, but to the trans-meridian (East-West) distance travelled.
  
  For instance, a ten hour flight from Europe to South Africa does not cause jet lag because most of this flight's route is from North to South. On the other hand, a five hour flight from the west to the east Coast of the United States will result in some jet lag.
  
  Overall, the body adapts better when travelling west because you are literally extending the day, rather than travelling east, when the day is being shortened. The human body finds it easier to cope with going to bed later than usual, rather than trying to get to sleep earlier than usual.


• Sleep routine - people who have a strict sleep routine, for example those who go to bed at the same time each night, are more likely to be affected by jet lag. Since babies and children are able to sleep at any time of the day, they tend to adjust to new time zones more easily. This is one of the reasons babies and children are less affected by jet lag than adults.


• The influence of sunlight - sunlight is a key factor on the internal clock. This is because the pineal gland, a part of the brain that influences circadian rhythms, reacts to varying levels of environmental light. Some cells in the retina of the eye (the tissue at the back of your eye) transmit the indication of light-levels to an area of the hypothalamus, a part of the brain. The data is then sent to your pineal gland. At night, the pineal gland releases the sleep-promoting hormone melatonin. During the day, melatonin production stops. As a result, you may be able to ease your adjustment to your new time zone by exposing yourself to daylight in that new time zone.

What are the symptoms of jet lag?

Symptoms of jet lag can vary from person to person. An individual's severity of symptoms will depend on various factors, including age, how many time zones he/she has travelled, overall health and some other occurrences before, during and after the trip.

Most people will only feel symptoms of jet lag when crossing at least three time zones, although some people also experience mild symptoms on shorter journeys.

• Sleep disturbance - The most frequent symptom of jet lag is a disturbed sleep pattern. Jet lag often makes the person feel tired and also unable to sleep at the correct times. People may typically be awake during the night and feel incredibly sleepy during the daytime.

Other symptoms of jet lag can include:


• Anxiety
• Clumsiness
• Confusion
• Constipation
• Diarrhea
• Difficulty concentrating
• Earache
• Fatigue
• Generally feeling unwell
• Headaches
• Indigestion or digestive problems
• Insomnia
• Irritability
• Lack of energy
• Light headedness
• Loss of appetite
• Memory problems
• Mild depression
• Moodiness
• Muscle soreness
• Nausea
• Sweating
• Swollen feet

What are the risk factors of jet lag?

A risk factor is something that increases the probability of developing a condition or disease. For example, regular cigarette smoking increases your risk of getting lung cancer. Therefore, smoking is a risk factor for lung cancer.

The known risk factors for jet lag are:

• Being a frequent flyer. Pilots, flight attendants and business travelers are most likely to experience jet lag.


• Being an older adult. Older adults may need more time to recover from jet lag than younger adults. The problem tends to get worse the older we get.


• Flying East. It is harder when flying east, when you "lose" time, than when flying west, when you gain it back.


• Number of time zones crossed. The more time zones someone crosses, the more likely they are to be jet-lagged.


• Existing sleep disorders. - people with existing sleep disorders may find they suffer more from jet lag than other people.


• Fear of flying - fear of flying may cause jet lag after the trip out. It is thought the traveler may be worried about the trip back, causing him/her to have sleeping difficulties.

What are the treatment options for jet lag?

Because the experience of jet lag varies among individuals, it is difficult to assess the efficacy of any particular cure.

• Slow and gradual fine tuning - slow gradual fine-tuning during several days while maintaining the regular length of 7 to 8 hours of sleep can reduce tiredness and avoid depression. If the objective is to catch up with local time, it is recommended that the traveler refrains from taking naps during the afternoon. Eating an early dinner rich in carbohydrates and low in protein can be helpful.


• Medication - generally, jet lag usually does not require treatment. However, if you're a frequent traveler continuously bothered by jet lag, your doctor may prescribe medications or light therapy:
  
  
  • Nonbenzodiazepines such as zolpidem (Ambien), eszopiclone (Lunesta) and zaleplon (Sonata)
  • Benzodiazepines such as triazolam (Halcion)
  
  These medications may help you sleep during the flight and for several nights afterwards. Side effects are uncommon but may include nausea, vomiting, amnesia, sleepwalking, confusion and morning sleepiness. Although these medications appear to help sleep duration and quality, they may not diminish daytime symptoms of jet lag. Anybody considering taking these medication should talk to their doctor.


• Light therapy - the body's internal clock or circadian rhythms are influenced by exposure to sunlight, among other factors. When someone travels across time zones, the body must adjust and reset to a new daylight schedule. This allows you to fall asleep and be awake at the appropriate times.
  
  Light therapy can help ease that changeover of jet lag. It involves exposing your eyes to an artificial bright light or lamp that simulates sunlight for a specific and regular amount of time during the time when you are meant to be awake. This may be useful, for example, if you are a business traveler and are frequently indoors and away from natural sunlight.


• Caffeine - using caffeine in the amounts you encounter in beverages like coffee, espresso and soft drinks may help offset daytime sleepiness. However, it's best to time caffeine use so that it does not interfere with planned bedtime, because it may make it even more difficult to fall asleep or sleep soundly. Therefore it is essential not to consume any caffeine within six hours before planning to go to sleep.


• Melatonin - melatonin is a hormone our body produces. In the evening it tells the brain that it is time to go to sleep.
  
  Some jet lag remedies contain melatonin and are meant to help you sleep at night when the body is finding it hard to adjust to the new time zone. Studies on the benefits of melatonin as a sleep aid, and perhaps as a treatment for jet lag have had mixed results. However, recent studies appear to indicate that melatonin helps you sleep during times you normally wouldn't not be sleeping, so it could be beneficial for those with jet lag.
  
  Even so, many say the evidence for melatonin supplements is not compelling. Although many individuals claim to find them helpful, melatonin supplements are not currently licensed to be marketed for jet lag prevention or treatment. If you have any doubts you should discuss this with your doctor.
  
  Canadian researchers found that there seems to be no evidence that melatonin helps treat secondary sleep disorders or prevents jet lag.


• Sunglasses - if you are going on a long plane trip you could benefit from wearing sunglasses as they can reduce the effects of jet-lag, say researchers from the Edinburgh Sleep Centre, Scotland.
  
  Some frequent fliers have their own favorite alternative jet lag cure that works for them, such as aromatherapy, homeopathy or special diets. Most alternative jet lag therapies are not harmful and may be worth a try if nothing else helps.

Prevention of jet lag

There are a number of steps that people can take to help decrease the effect of jet lag:

• Before traveling
  
  
  • Change the sleep routine - Try to change your sleeping routine a few days before you are due to travel. If you are travelling east, try going to bed an hour earlier than your usual time. If you are travelling west, do it the other way round and go to bed an hour later.
  
  
  • Get enough sleep - it is important to get enough sleep before travelling. Flying when you have not had enough sleep can make jet lag worse.
  
  
  • Keep calm - airports can sometimes be stressful. Try and keep as calm and relaxed as possible because being tense can make jet lag worse.
  
  
  • Change mealtimes beforehand - researchers from Beth Israel Deaconess Medical Center in Harvard Medical School, Boston, found that they could shift mice's circadian rhythm or body clock by controlling food availability, suggesting that changing patterns of mealtimes might help humans adjust their body clock too, for instance to cope with jet lag.


• During the flight
  
  
  • Avoid alcohol - avoid drinking alcohol because it can aggravate the symptoms of jet lag. You may think that a few drinks will help ease you into your trip and relax you. Unfortunately, alcohol and jet lag do not mix.
  
  
  • Change your watch - when you board the plane, you may find it helpful to adjust your watch so that it matches the time of your destination. This will help you to adjust more quickly to your new time zone.
  
  
  • Drink plenty of fluids - make sure that you drink plenty of fluids during your flight. If possible, you should also ensure that you are well hydrated before and after your flight. The best fluid is water.
  
  
  • Get some sleep - if it is night time at your destination while you are on your flight, try and get some sleep. Some people find it helpful to use ear plugs and eye masks.
  
  
  • Keep active - make sure that you keep active if you are flying long distances. Walk around the cabin occasionally, and regularly stretch your arms and legs when you are sitting down.


• When you arrive
  
  
  • Avoid napping - try not to nap shortly after you arrive at your destination. You may be tired from a long flight, but try to stay active until it is the correct time for you to sleep. This will help your body adjust more quickly.
  
  
  • Get into your new routine - try to get used to your new routine as soon as possible. This means eating meals and sleeping at the right times for your new time zone, and not the time you would normally be eating and sleeping back home.
  
  
  • Spend time outdoors - try to spend as much time outdoors as you can. Natural light is a very effective way of getting your body to adjust to a new schedule.
  
  
  • Stay hydrated - drink plenty of water before, during and after your flight to counteract the dehydrating effects of dry cabin air. Dehydration can make jet lag symptoms worse. For the same reason, steer clear of alcohol and caffeine, both of which dehydrate you further.
  
  
  • Stay on your new schedule - once you reach your destination, try not to sleep until nighttime, no matter how tired you are.
  
  
  • Try to sleep on the plane if it's nighttime at your destination - earplugs, headphones and eye masks can help block out noise and light. If it is daytime where you are going, resist the urge to sleep.

Written by Stephanie Brunner


Copyright: Medical News Today
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