Circadiana is a new blog written by someone who is apparently a researcher in sleep behaviour. This first post is a long, but fascinating read. Here's an excerpt:
It appears that we are slowly waking up to sleep problems (pun intended). More and more companies are allowing naps, and even providing nap-rooms. More and more school districts are moving high-school morning schedules later, as during teenage years, under effects of sex hormones, the circadian clocks are all temporarily "owlish". Adolescents are not crazy and lazy - they physically cannot fall asleep at a normal bed time, and physically cannot awake and feel rested early in the morning (elementary and middle school kids can, as their hormones have not surged yet).