Jet lag is a fairly common problem among people who undertake international travel, especially transmeridean travel. Jet lag is not seen if the journey does not involve transmeridean travel, even if journey is of several hours duration, e.g. traveling from London to Cape Town, a 7 hours journey.

What is jet lag?

The medical term of jet lag is “desynchronosis”. Jet lag is a condition due to alteration of normal cicardian rhythm of sleep by transmeridian air travel and there is disturbance in sleep, tiredness etc. Jet lag occurs due to transmeridian (east-west or west-east) air travel. More than 75 million people undertake transmeridian air travel annually and many of them experience jet lag.

Jet lag does not occur due to air travel, but due to transmeridian air travel and length of air travel is not important. What is important is the number of time zones a traveler is traveling, e.g. if a person travels from London to Cape Town in South Africa, which is approximately 10 hours journey by air, will not suffer from jet lag, because both these cities are in similar time zone (no transmeridian travel involved). Whereas travel from London to New York will cause jet lag, although journey is less than 10 hours, also a person may suffer from jet lag if he/she travels from East Coast to West Cost or vise-versa in USA which is approximately 5 hours journey by air, because they are in different time zones.

Why jet lag occurs?

When we travel and cross over to another time zone very fast (as is the case in air travel) our body loses synchronization with destination time as our body is adapted to the biological clock of home. For example if you sleep at approximately 11 PM everyday and you travel to a place which is 12 hours east or west, you will feel sleepy at 11 AM in new location, because your body is accustomed to this rhythm. Secretion of many hormones and other chemicals are regulated by our sleeping pattern and according to biological clock, but this is disturbed in long transmeridian air travel, which causes jet lag. Crossing of only one or two time zones may cause only minor problems and only in few individuals, if at all it causes jet lag, but if number of time zones crossed is more it can cause jet lag in more people.

Crossing of International Dateline does not cause jet lag if the crossing is not more than one time zone.

How long you may suffer from jet lag?

Jet lag typically last from 2 days to 2 weeks (2-14 days), depending on the direction of travel, number of time zones crossed, the phase shifting capacity of the traveler and also on the age of the traveler (younger travelers tend to adjust faster and recover from jet lag faster than older individuals). Out door activities also makes recovery faster from jet lag and staying indoor in hotel room will slow recovery from jet lag. Outdoor activities hasten recovery due to exposure to bright light (sunlight).

The duration of jet lag generally depends on the number of time zones crossed and generally the recovery takes approximately 1 day for every time zones cross towards eastwards and 1.5 days for every time zones crossed westward.

If the time difference is more than 12 hours, subtract the actual difference from 24 to get the actual difference.

What are the symptoms of jet lag?

The common signs and symptoms of jet lag are excessive daytime sleepiness, difficulty in falling asleep (known as sleep onset insomnia), frequent arousal from sleep (especially in the later half of night or after 12 midnight) and gastrointestinal discomfort or digestion problems. Headache, fatigue, irritability, disorientation, mild depression etc. are also seen in many patients with jet lag.

Treatment of jet lag:

There is no standard treatment for jet lag. No single drug is effective in jet lag. Laboratory testing suggests that “melatonin”, a pineal hormone in minute doses (in micro gram dose) can improve sleep efficiency. But melatonin is effective only if taken when the level of melatonin is low, which normally occurs during daytime only. But melatonin is neither approved (not approved by USFDA or other agencies) or is proved safe and efficacious for treatment of jet lag. Further study and clinical trials are required for melatonin to be used for jet lag and other sleep disorders.

The individuals suffering from jet lag need to be managed based on individual need as the symptoms also vary in different individual. In other word the management of jet lag needs to be individualized, as no single treatment/management can be applied to all individuals with jet lag.

How to prevent/reduce jet lag?

To prevent or reduce the duration of jet lag it is important to go outdoors instead of staying indoor or inside hotel rooms. Exposure to bright sunlight helps human body to adjust to the local circadian rhythm of sleep which is related to sun.

Try to avoid loss of sleep prior to travel and take a nap whenever possible before air travel, which will help to remain wake for longer time.

The following steps can be taken to prevent jet lag:

• If possible break a long journey with a halt in between.
• If traveling towards east you should go to bed earlier than usual and if flying towards west go to bed later than usual for few days before journey. This will reduce jet lag.
• Avoid coffee, tea or alcohol and take plenty of liquids during flight.
• Spend more time outdoors and get exposed to bright light at the destination which will help in adjusting to new time.
• Prepare yourself psychologically and adjust your watch to the destination time halfway through the flight and start thinking in terms of your new time zone.
• Sleep on the flight, which will help to remain awake after arrival to the destination in new time zone.