MAPPING THE DARKNESS

An award-winning science writer takes us on a tour of the research into sleep.

Although we are asleep for about a third of our lives, for much of human history, its mysteries lay undiscovered. It was only in the 1920s that systematic studies began, and for decades, it was only a marginal field. “Just a century ago,” writes Miller, a contributing editor for Discover, “only a handful of scientists studied sleep—and not a single one did so full-​time.” The author tracks the history with biographies of the key figures as they devised a series of experiments, which included two of the scientists living in a cave for a month to assess sleep patterns. Studies showed that 24 hours was the natural cycle for humans, although the rhythms of sleep and wakefulness are disrupted by work shifts and artificial lighting. The development of machines that could measure electrical activity in the brain revealed the various stages of sleep, including dream states, and helped researchers understand the connection between sleep disorders and other health problems. The Challenger space shuttle disaster in 1986, which was traced partly to sleep deprivation in two engineers, sent researchers in a different direction. Within a few years, a lack of sleep was tied to low productivity, accidents, and near misses. Further study revealed that teenagers were often sleep-deprived, a finding that led to changes in school hours. “Despite decades of studies showing that adults need seven to nine hours for optimal health, large swaths of the world’s population get less than the recommended minimum,” writes Miller. Furthermore, “our growing attachment to digital devices makes it harder to disconnect from waking consciousness, and the blue light from screens throws our circadian clocks into confusion.” Though the narrative is occasionally sluggish, the author provides an interesting examination of an issue that affects us all.

Miller shows us how a good night’s sleep came to be recognized as critical for health and development.