I was listening to a scientist on public radio a few years back who was talking about this research. The most interesting part, I thought, was about sleep deprivation in adults and how your body will reclaim sleep from you whether you like it or not. It does this by enforcing "micro-sleeps" on you, where your higher consciousness just blanks for out for a few seconds. The speaker speculated that this might be a factor in the increase in morning-time traffic accidents around DST time changes...