Most people don't realize it, but even for those who are committed to a lifestyle of health and activity - they are lacking a significant component to their program.
Our culture seems to have developed an attitude that sleeping somehow shows weakness - it's a badge of honor to get by on 3-4hrs sleep. Unfortunately, our performance lags significantly the more sleep we miss. This can have immediate and deadly repercussions (truck drivers, or medical residents working 36hrs on call in the emergency room) or smaller, yet still harmful results on each of us as individuals.
I think in many ways it's a matter of redefining our attitude - I know that this is something I still continue to work on. Sleep is not "optional", any more than eating and training - it's a critical component to our overall health. Not only does being properly rested allow us greater mental acuity and improved performance in training - this is also when we actually make our gains. Many people believe that the workout is the key part - but if you're not recovering properly then, in fact, all you're doing is tearing yourself down without the reciprocal rebuilding that is necessary for improvement.
So the next time you look at the clock and realize that if you get to bed in the next 30mins you'll be able to sleep for 7-8hrs, don't try to fit in "one last task". Put what you're doing away - get a good book and a hot (non-caffeinated) tea and allow your mind some time to unwind before crawling into bed.