Adult and adolescent sleep patterns.
People complain they're working more and sleeping less.
I can get a package to California by tomorrow, but somebody's got to stay up all night to get it there. There is also this ethic that we're stronger than our need to sleep. People think they're showing loyalty and effort by ignoring their biological need. The most poignant example, for me, is the Challenger tragedy. The shuttle people preparing for that launch were pulling double shifts.