Crux of The myth of the eight-hour sleep by Stephanie Hegarty:

  • Without artificial lighting, the natural sleep pattern is: “a first sleep which began about two hours after dusk, followed by waking period of one or two hours and then a second sleep.”
  • This sleep pattern was found in sleep experiments, historical documents, and anthropological data.
  • The waking period in the middle of night was commonly used for meditating on dreams, chatting, prayer, or sex.