Jetlag, also called desynchronosis and flight fatigue, is a temporary disorder that causes fatigue,insomnia, and other symptoms as a result of air travel across time zones. It is considered a circadian rhythm sleep disorder, which is a disruption of the internal body clock.
In general, the body will adjust to the new time zone at the rate of one or two time zones per day.
Is it dangerous? Generally not, at least not directly unless you need to drive or operate heavy machinery. But it is unpleasant and unwelcome, and in extremes it can be harmful. Twice a year we have an experiment running with X millions of people, and it shows the negative consequences,
including X% of higher occurrence of …..?stroke? and x% higher occurrence of suicide in men. This experiment is called daylight savings time and the change is just 1 hour. So if you travel across several timezones, you better watch out for yourself.