What is jet lag?

Internal sleep clock is out of sync from the local time after going to another time zone, occurs for 1 or 2 days after travel (may include neuropsychiatric issues and insomnia). Going eastwards is harder than westwards. For short travels it is better to stay on same time, for longer ones adaptation is better There are measures taken pre and post flight, and hypnosis during flight has a risk of parasomnia (sleep walking)