Jet lag is a condition marked by fatigue, insomnia, and irritability that is caused by air travel through changing time zones leaving a a person feeling "out of sync" with the local time at his or her destination.
The 'bodyclock' mechanisms in people, also known as circadian rhythms, are under neuro (nerve)-endocrine (glandular) control, and under normal circumstances, function in a synchronized manner. The symptoms known as 'jet lag' are not due to fatigue, but to de-synchronization of your body rhythms.
Picture how experiencing any of the following symptoms of jet lag could ruin your business or pleasure trip.