Jet lag. A medical condition associated with air travel, the symptoms of which include disorientation, swelling of the feet and, most notably, extreme fatigue. A long flight, which might or might not include the changing from one time zone to another, can make a person lethargic for days, even weeks, after landing. Some compare the fatigue from jet lag to that of mononucleosis. And that's basically something a group of Irish soccer fans are asking the government for.