Superhuman or super sleepy: Short sleepers function on four hours

For most of us, setting the clock forward in the spring is a sad occasion, a sign that we're losing an hour of sleep.

Daylight saving time begins Sunday at 2 a.m. in most of the U.S. -- except for Hawaii and Arizona.

But for some genetically blessed people, a loss of one hour of sleep is not a problem. In fact, sleeping fewer than the recommended seven or eight hours is the norm. They naturally feel refreshed and ready to go -- at 4 a.m.