Jet Lag

By: Ms Catherine Guo, Pharmacist at Unity Marine Parade

First seen in Lifestyle Magazine (April 2014), pg 102. This article is an unbreached version of the print edition.


Jet lag is a condition caused by disruption to the body’s own biological clock or circadian rhythm resulting from rapid, long distance travel. The severity of jet lag depends on several factors including the direction of travel, number of time zones crossed and age. Travelling to the east can cause jet lag more often, and the more the number of time zones crossed, the more severe the symptoms are. Young travelers also tend to adjust faster than older individuals. However, between individuals of the same age, there might still be significant variations.

When travelling to a different time zone, the body, instead of preparing to sleep during the night, might instead be faced with the morning or midday light. A person is therefore out of synchronization with the time zone he or she is accustomed to and cannot immediately adapt to this difference, as the body is still reacting to the old time zone. This can lead to problems with sleep and other complications.


Symptoms of jet lag include:

  • Sleep issues such as insomnia and disturbed sleep
  • Fatigue and impaired concentration during the day
  • Indigestion, constipation or diarrhea
  • General feeling of unwell such as headaches
  • Irritability

All these symptoms may affect work performance, and also the vacation experience.

The body clock and circadian rhythm

Our body follows a regular rhythm across the day and throughout the night. This body rhythm regulates body temperature, hunger, bowel habits, digestion, blood pressure, alertness and hormonal secretion. These processes are also adjusted to the environment as well.

Various factors contribute to the natural rhythm of this body clock. Natural light is thought to be a major factor. Hence, exposure to sunlight in the morning can advance the body clock while exposure in the evening may delay it.

Melatonin is a hormone secreted at night and suppressed by light. Therefore, high melatonin levels in the morning can delay the body clock. In addition, melatonin induces temperature changes in the body which promote sleep while a lack of melatonin in the body increases alertness.

What can be done?

Since light is an important stimulus to the body clock, trying to stay awake during the day and sleeping when dark helps the body to adjust. Avoiding naps during the day, no matter how tired, helps to sleep when night falls. In addition, try to be exposed to sunlight as much as possible during the day and combine with exercise such as jogging and walking for better results. During travelling, try to sleep on the plane as much as possible if the destination is night time, and try to resist sleep as much as possible if the destination is day time.

Eating meals at the correct time during the time zone of your destination also promotes the body to make a shift faster. It is also advisable to relax the body and prepare for sleep during the night. For instance, taking a shower, relaxing with music and being in a comfortable, pleasant environment, facilitate sleep. Try to avoid alcohol, nicotine and caffeine within 6 hours of your intended sleeping time.

It also recommended to be well rested before the flight and stay hydrated to minimize jet lag as much as possible.

Melatonin supplements

The effectiveness of melatonin supplements has been disputed. While some studies and reviews suggest doses of 5mg daily at bed time (higher doses are not more potent) are efficient at preventing or reducing jet lag, other reviews have been less promising. In addition, there is a lack of conclusive studies on the adverse effects of melatonin. Although short term use appears safe, there have been reports of side effects in epileptic patients and possible problems when taking it with warfarin (a blood thinning drug). Furthermore there is a lack of evidence regarding its use in children. Hence, individuals with medical conditions as such epilepsy and children should avoid use and seek medical advice.

Other supplements such as valerian root, homeopathic preparations and aromatherapy (essential oils) are also available to help with sleep and jet lag, but effectiveness varies between individuals.

There are also medications (such as benzodiazepines) that can help with sleep for people with serious jet lag problem. These medications have to be prescribed by a doctor.


Jet lag cannot be prevented fully and severity depends on individuals. However, the symptoms can be minimized by practicing certain habits to help the body adjust to the new time zone. Over the counter supplements are available to help, and for serious cases whereby sleep and performance is greatly affected, a doctor’s visit is advised.


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