1. a temporary disruption of bodily rhythms caused by high-speed travel across several time zones typically in a jet aircraft.
2. physical condition caused by crossing multiple time zones during flight. The condition is generally believed to be the result of disruption to the circadian rhythms(i.e. the "light/dark" cycle) of the body. It can also be exacerbated by experiencing sudden changes in climate or seasonal conditions, as well as the reduced oxygen partial pressure and low humidity commonly experienced in the cabin of an aircraft.
3. a condition that is characterized by various psychological and physiological effects (as fatigue and irritability), occurs following long flight through several time zones, and probably results from disruption of circadian rhythms in the human body. Other symptoms of jet lag include anxiety, constipation, diarrhea, confusion, dehydration, headache, irritability, nausea, sweating, coordination problems, and even memory loss. Some individuals may report additional symptoms, such as heartbeat irregularities and an increased susceptibility to illness.
Blah blah blah. Not to say that they're not correct, but they're definitely incomplete. Let's redefine that, shall we? So, they all say that it's a physical condition, so ok we'll keep that; caused by travel (no, really? Who would have thought???); intensified by climate and season changes (I have no problem believing that as we went from 35 to 10 degrees); the effects being fatigue (uhu) and irritability (not sure about that one, even though I most probably was very irritable this morning at 4:25 am as I lay wide awake in my bed after just a few hours of sleep.) As for the list of other symptoms they are quite scary. I'll just keep confusion, as I do feel quite disoriented since I landed. But what about the sleepless hours you spend in bed exhausted at night? During my many insomniac hours last night, I first started to blame the severity of my jetlag on my age. But as the hours went by, I remembered the severe insomnia I suffered as a child returning every Summer from the States. Honestly I don't think we can take age as a factor. But we should definitely add that you barely feel any jetlag when you travel to your holiday destination but really feel it when you come back home. Pretty illogical if you ask me, but that's the way it works.
So we now have a physical condition caused by travel and experienced mostly when returning home, intensified by climate and season changes, which causes fatigue, confusion, insomnia, irritability, and many other more severe effects.
Yup, that's it. But maybe I should add that is also causes weird and abnormal behavior cause I don't think it's normal I just spent half an hour writing about this, when I am actually swamped at work!