THE NOCTURNAL BRAIN

A fine popular-science account of sleep, mostly about when it goes wrong.

“We think of sleep as a tranquil act, when our minds are stilled and our brains are quiet,” writes Leschziner, a consulting neurologist and sleep physician at Guy’s Hospital in London. He continues, “the only awareness we might have of something happening in the night are the fragments of a dream.” Of course, like the author, most readers know that this is not the case. The author follows a straightforward format. Each chapter features a patient who describes their miseries, usually accompanied by frustrating visits to a clueless family doctor. The author investigates, makes the correct diagnosis, and describes the sometimes-happy outcome, all accompanied by asides to the reader explaining the science. Many sleep disorders are forms of brain disease. Narcolepsy, which causes intense daytime sleepiness, may be caused by the lack of a chemical that regulates wakefulness. Some problems occur when systems are out of sync. Dreaming occurs during a sleep stage when the body is paralyzed—which is why it’s difficult to cry out or move during a nightmare. Without paralysis, dreamers get up and do bizarre things. When paralysis occurs during waking, victims fall down; it’s called cataplexy. Even in a healthy brain, sleep and wakefulness are not clearly separate states, so almost everyone experiences lucid dreaming, odd sensory experiences that verge on hallucinations. Problems arise when parts of the brain controlling movement and emotion wake while regions influencing rational thinking remain asleep. Sleepwalking is the best known phenomenon, but there are others, including sleep talking, sleep eating, and night terrors. Cures do occur, and many disorders respond to lifestyle changes, but others require the permanent use of drugs and/or devices. Most American writers would deal with the cost of treatment, but Leschziner works under the British National Health Service, so readers must be satisfied with entertaining stories and a painless education on the nature of sleep and its malfunctions.

Not groundbreaking but a useful entry in sleep-disorder literature.