I am so careful to get at least 7.5, usually 8 hours of sleep a night1  I've been doing this for a couple years and it makes all the difference in the world.  On the rare occasions that I don't sleep well, I can tell the next day, so I'm extra careful to get a good night sleep the next night.  I never have to use caffine to wake up, but then again I've always been one of those annoying morning people....drives my partner and co workers crazy!! :)