Jet Lag

Jet lag is a condition caused when we travel across time zones, and our normal circadian rhythms are disrupted. It is experienced in the form of physical and psychological discomfort. The symptoms may include excessive sleepiness, feeling depressed, reduced efficiency, and premature awakening.

The determining factor in the impact and experience of jet lag is how many time zones are crossed. Since time zones change only when travelling in east or west directions, north-south flights produce far less jet lag.


Effects of jet lag

It is easier to move our sleep and waking time forward rather than backward, making the day longer rather than shorter. Eastbound travel shortens the day or night, so travelling west produces less jet

lag. It is more  likely to be effected by jet lag by flying east because:

  • depending on the distance travelled, you lose several hours of sleep time
  • your body clock will only partially reset when changing time zones. The body clock takes an average of one day to adjust for each time zone crossed. A difference of four hours between home and local time may take you up to four days to adjust.

Impact and experience  of jet lag:

The impact and experience of jet lag varies dramatically between individuals.

How you are affected depends on many factors, including:

  • direction of travel (travelling west is easier)
  • physical fitness (better fitness improves circadian adjustment)
  • age (the effects of jet lag increase with age)

Symptoms of jet leg

One of the most common symptoms of jet lag is sleep disruption. This is likely to include:

  • difficulty getting to sleep at regular bedtime
  • waking up during the night and not being able to get back to sleep
  • fighting sleep during the day
  • problems with digestion
  • degraded performance on mental and physical tasks
  • mood changes
  • wanting to eat and sleep at times that are out of step with the local routine

This level of sleep disruption is likely to lead to insufficient sleep quality and quantity, and subsequent fatigue.

Easing the effects of jet lag

The most obvious technique for minimizing the effects of jet lag is maximizing sleep quality and quantity. Methods vary between individuals. These useful tips are recommended:

  • Set up your sleeping environment to minimize light and noise disturbance, and set the temperature to between 18 and 24°C.
  • Drink lots of water, dehydration and the dry air aboard aircraft can cause headaches and nasal irritation, which exacerbate the symptoms.
  • Avoid coffee and alcohol, which are diuretics and cause dehydration
  • Keep physically fit, people who are unfit tend to experience longer periods of jet lag.
  • Start adjusting sleep and eating times before you leave. Even shifting your bed and meal times by an hour or two can jumpstart the change in your body clock in the right direction.
  • Ensure you are well rested before the flight. Many travelers are tempted to stay up late, and get very little sleep before a flight so they will be able to sleep better upon arrival at their location. In reality, people who are already in sleep debt before a flight will experience more symptoms than those who are well rested.
  • Avoid overeating (especially salty foods)
  • Avoid motion sickness drugs when possible (they are depressants).
  • Move around and exercise wherever possible, throughout the flight or during stopovers.


Source: Fatigue Management Strategies for Employees, Transport Canada