i think it's a shame how many people think coffee will make up for <7 hours of sleep on a regular basis. i wish a chart like this was more publicized.<p>if i get less than seven hours, it always throws the rest of my day off. on the flipside, if i ever sleep in on a weekend more than nine hours, i'll feel lethargic and tired like i'm sleep deprived.<p>thanks for passing along, now i'll be doing the same :)