Information about what jet lag is and how it may best be treated.
What is Jet-lag?
Jet-lag is a problem that is directly related to our ‘body clock’. Almost every function in the body is influenced by a ‘master’ body clock which is located within the brain and sets our ‘circadian rhythms’. These allow our body to predict changes in the environment and help to synchronize sleep and activity over a 24-hour period.
The most important factor in setting our body clock is the cycle of light and darkness. However, our body clock does not cope well with rapid and large changes in the timing of environmental signals like light, which is what happens when we fly quickly across world time zones.
‘Jet-lag’ is the term used for the symptoms you may feel while your body clock adjusts to time in the new location. Symptoms of jet-lag include feeling tired during the day in the new time zone, and yet experiencing disturbed sleep at night, feeling less able to concentrate or to motivate yourself, decreased mental and physical performance, increased incidence of headaches and irritability, loss of appetite and gastro-intestinal problems such as constipation.
How does Jet-lag differ from Travel Fatigue?
Any journey, particularly if more than 3 hours, can cause discomfort and tiredness whether you are travelling by car, bus, train or aeroplane. You may spend long periods in a cramped position and there may be other stresses such as delays, unplanned stops or detours. These symptoms do not last long and often improve after a rest, some light exercise, or a shower or bath. You will usually experience symptoms of travel fatigue after any long-haul flight, but you will only suffer from jet-lag if you cross several (probably more than 3) time zones. You only cross time zones if you travel eastward or westward, so you won’t suffer from jet lag if you fly more or less directly north or south, for example from the UK to Africa or from North to South America.
What affects the severity of jet-lag?
The severity of jet-lag depends on the number of time-zones you cross and, to a lesser extent, on the direction of travel. For most people, the symptoms are worse if they travel eastwards than if they travel westwards. The symptoms may also depend on whether you are a morning-type “lark” or an evening-type “owl”. There is little evidence that jet-lag symptoms are different between men and women, or between older and younger people.
Atkinson G. (2013) Jet Lag Type. In: Kushida C. (ed.) The Encyclopedia of Sleep, vol. 3, pp. 41-43. Waltham, MA: Academic Press.
Sack RL (2010) Jet Lag. New Eng J Med 362: 440-447.
Waterhouse J, Reilly T, Atkinson G, Edwards B (2007) Jet lag: trends and coping strategies. Lancet 369: 1117-1129.
This information is based on an article written by Prof. Greg Atkinson, Health and Social Care Institute, Teesside University, Email: firstname.lastname@example.org
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