Some years ago, I read Roger Ekirch’s At Day’s Close, a book about the history of sleep. Ekirch discovered that before the arrival of artificial light, English people had customarily had two sleep periods each night. People retired soon after dusk, and rose again at dawn. But their nights were divided into two sleeps, with a waking interval between.
I became curious, and found to my amazement that I could trigger the pattern in myself. I went to bed earlier, and suddenly waking at 2 a.m. wasn’t a source of anxiety, but an opportunity. I would stay awake for an hour or two, reading or musing, then sleep again till rising for work. I was stunned by the ease with which my body slipped into this rhythm, my DNA recalling the lives of the weavers and wheelwrights of Ekirch’s study.
