My favorite thing to do to get rid of stress is take a nap! or a walk!  It seems like sometimes if you try to hard to get everything done, you just get more and more tired and more and more of a headache.  Sometimes it's best just to turn off everything and get away from it for awhile.  A lot of times that means a nap, rest your brain!  Otherwise, a walk is always nice and can reenergize you too.