The Nocturnal Brain: Nightmares, Neuroscience, and the Secret World of Sleep

by Guy Leschziner

It is incredibly common, when we meet after the sleep study, and I ask how they slept, to hear: ‘I slept terribly that night.’ But when we look at the sleep study, it shows a very decent night’s sleep — seven or more hours, with lots of deep sleep — despite the person in front of me being adamant that they only slept for an hour or two. This type of insomnia is termed ‘sleep state misperception’ or ‘paradoxical insomnia’, and is likely to explain why there is a huge overlap between the sleep studies of patients with insomnia and normal sleepers. Something about the way the person experiences sleep is different. Perhaps it is the quality of sleep, something we cannot gauge with our standard technique of measuring sleep, the polysomnogram. Or maybe it is as simple as the brain filling in time between the brief awakenings that are a feature of normal sleep, perceived as wakefulness by someone predisposed to this form of insomnia, rather than the deep sleep seen on the sleep study.