Jet Lag is the feeling of extreme tiredness and other physical effects to the body after flying across numerous time zones. The result can be confusion and the inability for your body to adapt to the current time zone.
Our body had a circadian rhythm which is a 24 hour cycle of physical, mental and behavioural changes otherwise known as our body clock. Basically our circadian rhythm regulates everyday goings-on like eating, sleeping, blood pressure and our body temperature. It is driven by internal factors within our body and also external changes in our environment such as light and temperature.
When we cross numerous time zones, this disrupts our circadian rhythm. The more time zones crossed in one flight, the more severe the disruption. A long flight in the same one or two time zones would not upset our body clock.
The crossing of the time zones causes our circadian rhythm to be out of sync with the destination time. The external signals such as day and night are different to what our internal clock expects.
The body can’t immediately realign its rhythm so this causes the tiredness and confusion. As long as these internal and external factors are out of sync you will feel jet lagged.