From a very interesting Wall Street Journal piece on sleep, we
learn some history about how humans used to get two sleeping
chunks at night: So why is sleep, which seems so simple,
becoming so problematic? Much of the problem can be traced to
the revolutionary device that’s probably hanging above your head
right now: the light bulb. Before this electrically illuminated
age, our ancestors slept in two distinct chunks each night. The
so-called first sleep took place not long after the sun went
down and lasted until a little after midnight. A person would
then wake up for an hour or so before heading back to the so-
called second sleep. It was a fact of life that was once as
common as breakfast—and one which might have remained forgotten
had it not been for the research of a Virginia Tech history
professor named A. Roger Ekirch, who spent nearly 20 years in
the 1980s and ’90s investigating the history of the night. As
Prof. Ekirch leafed through documents ranging from property
records to primers on how to spot a