Since I'm still a student I don't have to deal with constant stress as a part of my daily work routine, but there are situations (like now, that's why I'm posting this) when I'm preparing some big and important exam in a moment which may not be missed for any price.
Usual consequencies of such pressure are insomnia, nervous behaviour, stomach craving for food (but I don't gain weight, just lose it) and some minor psychosomatic disorders like dandruf for instant (yes, that sucks).
The biggest problem is insomnia, ofcourse, which is caused by me not succeding in stopping thoughts - at least, that's my subjective feeling.
So I either read something amusing and completely different compared to what I study or I go for a long walk and a relaxing chat with someone.
Periods like this mostly last for about 10 days, and somwhere in the middle I usualy experience a great anxiety attack thinking that everything I do is worthless, like the world is colapsing. But, as I realy do understand the way my body and mind function, I use that day to take a break, I even go out in the evening and let those irational feelings to go away. And they do

After that 'peek' my concentration rises to heaven and eating and working seem like only things I need in life.
Perhaps the most important thing is knowing that the phase I'm going through has it's end.