My Mind Draws a Blank

Ha ha ha... Laugh all you want and tell all the blonde jokes you want (for those of you who know my natural hair color). But you know the feeling...You work, work, work, and go, go, go, on a big project or something like that and then whatever you were working for happens and the time passes and BAM! just like that life goes back to normal. Then your brain, that was so overworked five minutes ago now has nothing to do...