In previous posts I have referenced the importance of sleep and the many benefits of a sound (8+ hour) night of sleep, but I haven't addressed the side effects of poor sleep. One of the most common adverse effects associated with a night of poor sleep is insulin resistance (the thing that we are trying to avoid through a solid diet and smart exercise).
I know what you are thinking, "It won't effect my insulin resistance if I don't get a good night of sleep every once in a while, right?" It seems logical that skimping on sleep every once in a while would not have any negative effects on our bodies, but in reality this preconceived notion is wrong.
A recent article in Science News states that "one sleepless night can induce insulin resistance in healthy people." (http://www.sciencedaily.com/releases/2010/05/100505091632.htm) The article references a study published in "The Journal of Clinical Endocrinology & Metabolism." The study tested blood glucose and insulin levels in participants after one night of good quality sleep and one subsequent night of poor sleep. After the night of poor sleep the participants were significantly more insulin resistant than they were the day before.
So if you are a healthy, insulin-sensitive person do not take your health for granted, get your rest.