The Hidden Mind

Who we are and how we decide

The Strange Science of Sleep

What does science tell us about the hours after bedtime?

"Dreamland: Adventures in the Strange Science of Sleep" by David K. Randall

When discussing evolution, we are often reminded that proliferation requires feeding, fleeing from predators, and reproducing with verve. And yet this same evolutionary process has endowed many animals, from giraffes to fruit flies, with a period of mandatory downtime. It’s as if the latest laptop computer or iPad were to arrive with the warning: “Must remain switched off for at least seven hours a day”. Sleep is a puzzling affair. What's going on after bedtime?

There was a time when scientists thought the answer was “not much”. Sleep is one of the few aspects of our behavior that we cannot observe. You might regale a friend with tales from a weekend away, but the murky hours between nightfall and dawn will be omitted from your story. In Dreamland: Adventures in the Strange Science of Sleep, journalist David K. Randall offers a guided tour of this hidden aspect of our lives. The myriad facts here could easily fuel an evening’s discussion at the pub (although go easy – alcohol in the bloodstream leads to intermittent wakefulness, which is why you end up tired even after 8 hours). We learn why West Coast football teams have a better record in Monday Night Football, how wristwatch sleep monitors will be standard-issue in the US military by 2020, and that waking up from a nap at the wrong time may contribute to aviation accidents.

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Randall became interested in the subject after suffering from bouts of sleepwalking (“a less-than-peaceful part of my life”), which occur when the brain fails to release the hormones needed to paralyse the muscles during dreaming. You feel he is reassured by the science – it empowers him to understand something that would otherwise have been frightening and out of his control. While some sleepwalkers resort to chaining themselves to the bed to avoid jumping out of high-rise windows, others do not realize they are a danger to themselves and others – Canadian resident Ken Parks famously slept-walked out of his house to murder his parents-in-law in the 1980s. A third of our lives will be spent in the absence of consciousness; any acts committed in this period seem to be the work of automata. In one thoughtful passage, Randall explains that because the legal system has an all-or-nothing view of consciousness, it is difficult to decide whether sleepwalkers such as Parks should be held responsible for their actions.

Dreamland provides a useful scientific counterweight to the folk beliefs surrounding sleep and dreaming. The traditional Freudian interpretation of dreams is swept aside by a dispassionate account of reactivation of fragments of a busy day. Randall is at his best when weaving sleep into the narrative of modern life (“when sleep is more comfortable than ever and yet more elusive”). During the recent power outage in New York after Hurricane Sandy, I found myself drifting to an earlier bedtime, towards a natural sleep-wake cycle which we learn wasn’t always the eight-hour-block we assume it to be today. By the time we read that prescriptions for sleeping pills are accumulating faster than Facebook subscribers, we are rightly skeptical of the idea of a “normal” night’s sleep. But the author’s enthusiasm for anecdote is sometimes at the expense of the science. Theories of the function of sleep abound (a current front-runner is that it regulates synaptic plasticity in the brain1). I was thus surprised to find little exploration of why we sleep, aside from the acknowledgement that “whatever sleep does is so important that evolution goes out of its way to make it possible”.

Randall writes with the genuine enthusiasm of someone stumbling upon the science for the first time, and this book is easily accessible to the non-specialist. A flowing style and a brisk pace contribute to an entertaining read. But be warned: the paradox of sleep is that when thinking about it, you are unlikely to succumb to its charms. If Dreamland is on your nightstand, be prepared for time spent lying awake musing about the mystery of sleep.

1.         Wang, G., Grone, B., Colas, D., Appelbaum, L. & Mourrain, P. Synaptic plasticity in sleep: learning, homeostasis and disease. Trends in Neurosciences 34, 452–463 (2011).

Stephen Fleming is a neuroscientist at the Center for Neural Science, New York University.

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