Stephanie Hegarty, BBC:
We often worry about lying awake in the middle of the night - but it could be good for you. A growing body of evidence from both science and history suggests that the eight-hour sleep may be unnatural.
Hegarty outlines how people used to sleep in a segmented fashion - sleeping for four hours, awakening for one or two hours, then resuming sleep for another four hours. Research shows that our current eight-hour sleep cycle originated from society’s increased night activity and was intensified by the industrial revolution. Some hypothesize that the unnatural nature of the eight-hour sleep cycle has increased our anxiety, stress, and depression.