ever had to stay up to meet a deadline or wanted to stay up for the sake of it? why is it that once u get past a certain stage of fatigue or tiredness....u all of sudden become AWAKE!?! your heart begin to beat faster, you're restless and no matter how hard u try....you cant seem to be able to sleep? but then...after several hours....another phase infiltrates and u are now lethargic and is unable to keep ur eyes open, ur mouth is dry and your whole body aches...what is with that? is it because in that state of 'awakeness' ur actually in a serious state of fatigue, u r very tired but ur body is compensating, working harder to keep u awake? hence the increased HR and perceived alertness? then the next onset is when the whole body has over worked and is seriously in need of rest?....gah! it is definitely perceived alertness...how many mes hav i used the word seriously? grrrrrrr