Desynchronosis is the correct term for this challenge our body faces when we fly around the globe, but we take a look at what causes jet lag. The symptoms of jet lag occur when our bodies are out of sync with the time of day which creates confusuion causing tiredness and difficulty sleeping.
Desynchronosis is most commonly bought about by long distance air travel, but it is about much more than the length of the journey. For example, flying from one side of the globe to another along the same longitude, causes us no problems at all. So the key driver for jet lag is the messing up of the body clock and not the distance travelled.
Built in clocks
All animals, bacteria and plants have an internal body clock. Within humans, this circadian clock is situated in the base of the brain in a structure called the suprachiasmatic nucleus.
Fast and slow
The suprachiasmatic nucleus in humans, makes us active during daytime and slows us down at night time in order that we go to sleep. This clock builds in some stability to human behaviour, assisting your return to sleep if you awake at night.
When you fly to a different time zone, the change is too dramatic for the body clock to cope with as it is relatively slow to make asdjustments. There are cues from the environment that can help us adjust, like meal times and the cycle of light and dark. But how much adjustments needed to reballance your clock is dependent on how far you have travelled.
What you can handle
Your body can typicaly handle about 1-2 time zones per day in adjustment. This means an 8 hour difference between cities like London and Los Angeles will take about 4 days to get used to the change one way or the other.
The jet lag is harder to deal with when you fly east and forward in time than when you fly west. This is because the body clock tends to run slower than time, takeing about 24 1/2 hours to complete a day, so it is easier for the clock to delay because it naturally wishes to do so.
It isn’t 100% clear why some people can handle jet lag better than others but it may be to do with a combination of genetics, age and fitness.