Sleep deprivation is insidious and catches up to you incrementally, no matter how much you think you have "reconditioned" yourself. It slowly but surely weakens your memory, cognitive capabilities and emotional stability rendering you just a little more stupid and unpleasant with the passage of time. You don't notice it from one day to the next, but it is there and it is cumulative. Fortunately, it is reversible, but some of your resulting bone-headed decisions may not be. Also, there is the link between sleep deprivation and weight gain and a host of other physical implications, none of them pleasant.
http://www.sleep-deprivation.com/articles/effects-of-sleep-deprivation/index.php
http://www.sleep-deprivation.com/articles/effects-of-sleep-deprivation/index.php

