Jet lag

Jet lag is caused by fast travel across the time zones. Travel in modern jets means that the traveller lands either hours ahead, or behind the time their body was used to functioning in. Several time zones can be crossed during some long flights.

Our bodies have natural (Circadian) rhythms during which hormones are released at the time most suitable for function. The rhythms are set by external influences such as light, darkness, meals and social activities. This ensures that the body can respond to what it has learnt to need. ie melatonin is released at night-time to help us sleep. Shift workers can encounter similar problems to jet lag when their nights are turned into days and vice versa. Long distance travel and tiredness from lack of sleep aggravate jet lag.

Symptoms include

  • Altered mood, including irritability and loss of concentration
  • Impaired judgement
  • Daytime sleepiness
  • Inability to sleep at night
  • Intermittent dizziness
  • Stomach upset
What to do Choose the optimum time to travel and adjust sleeping patterns before travel if possible. eg if travelling west, try staying up 1 hour later each night for a few nights before travel. Likewise if travelling east, go to bed an hour earlier.

Try to choose a daytime flight that arrives early in the evening and then stay awake until the night time. If arriving in the morning is unavoidable, try staying up rather than going to bed, in order that you adjust to the new time zone.

Donít drink a lot of alcohol, but drink caffeine containing drinks, coffee or coke during the daytime.

Consider taking melatonin. This hormone is secreted naturally during the hours of darkness to promote sleep. Bright light inhibits its production. There is some evidence that it can help restore sleep when jetlagged. Further research is continuing.∑

Note: It is recommended that you change your watch during the flight to the time zone of your destination and try to eat/sleep according to that time. However, people with diabetes should keep to their home time for meals and injections whilst travelling and gradually adjust to the new time zone over a period of days.

Further information

This article published on
08 August 2005

Next review date 8/1/2013


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