The day I get home from any Europe trip I am incapable of doing anything, even working out a TV remote can send me into fog of frustrated rage. The day after I get home (and that's assuming I do sleep which is often impossible) I start to feel normal. The third day is the first that I can sensibly start to catch up on the previous 10 days paperwork/bills etc, possibly do some exercise or things 'normal' people do as a matter of course. There is always a panic the couple of days before I leave to get everything done so no disasters occur when I am away. Anyway, that's me and everyone is different - but the feeling I have is horrible and as everyone says, it's cumulative. Two years and it still feels a doddle. Five years of that routine every time you go to work you will start to understand how those who have been doing it for 20+ will be feeling.