Jet lag answer when does it occur?

It varies with the individual. Some people are not at all affected by it

Jet lag occurs when a person crosses couple time zone. For example, if you travel to the other side of the world, 12 pm becomes 12 am. Your body feels like it is lunch time but the environment says...

No, it shouldn't. Jet lag is the disruption of your circadian rhythm (your body clock) by the different time zones. So yeah, fasting shouldn't prevent jet lag.

That will depend on things like how far you are flying, from which direction you are approaching Ireland and how jet lag affects you in general.

A physician may recommend sleeping pills or prescription medication. New research into a melatonin agonist, LY156735 and genetic research into circadian rhythms suggests new treatments.