Cerebral Hygiene

Gavin Francis

  • The Mystery of Sleep: Why a Good Night’s Rest Is Vital to a Better, Healthier Life by Meir Kryger
    Yale, 330 pp, £20.00, May 2017, ISBN 978 0 300 22408 5

An apnoea is a cessation of breathing. When sufferers of sleep apnoea enter deep sleep, their airway becomes blocked by the tissues around their throat. They may gasp for air, and stir hundreds of times a night to a level just below conscious awareness. People with sleep apnoea wake up in the morning feeling as if they’ve slept normally, but are chronically tired because their sleep isn’t restorative. As a medical student in the 1990s I was paid to be a subject in sleep apnoea experiments. The condition had been described not twenty years earlier, and researchers were still trying to define how debilitating it could be. I’d cycle over to a sleep lab in Edinburgh’s psychiatric hospital, have electrodes glued to my head, then be shown to a room with a bed and a one-way mirror, on the other side of which sat a researcher, watching. They didn’t tell me on which nights my sleep would be interrupted: on these test nights, whenever I drifted into a deep sleep the researcher would play sounds through a loudspeaker over the bed, raising my encephalography (EEG) reading until I was nearly but not quite awake. The next morning I would be convinced I’d slept the night through, but the tests of mental agility and hazard awareness they put me through suggested otherwise. I’d crash the driving simulator and flunk at mental arithmetic.

Sometimes it would take me hours to fall asleep. I’m prone to insomnia and having electrodes glued to my head didn’t help. Neither did knowing someone’s research depended on my reliably nodding off. They would encourage me to read in dim light before trying to sleep. I remember I had a book of Borges’s stories on the go. They didn’t help either, until I reached ‘Funes the Memorious’, which includes a portrait of the eponymous mnemonist struggling to sleep. Following a head injury Funes has developed an ‘infallible’ memory. He ‘not only remembered every leaf on every tree of every wood, but even every one of the times he had perceived or imagined it’. To fall asleep is to release oneself from engagement with the world, but Funes can’t stop his mind teeming with details. When I first tried to sleep in the laboratory I couldn’t either. The only way Funes can find rest is to call up images of oblivion, such as being embedded in black obscurity, or imagining ‘himself at the bottom of the river, being rocked and annihilated by the current’. Lying awake in the lab, keenly aware that my thoughts were producing EEG readouts for the researchers’ scrutiny next door, I tried out the same visualisations as Funes – and fell asleep.

Funes’s circumstances are as extreme and fantastical as you’d expect from Borges, but his sleeping problems are ordinary enough. It’s estimated that about 10 per cent of the world’s population suffer chronic insomnia – a symptom, not a diagnosis – and the proportion who sleep poorly is higher still. Many of my own patients spend restless nights preoccupied by the details of their day, picking over regrets, or anxious about the future. I have seen several cases of Brexit-associated insomnia. The ubiquity of advertisements for mattresses is an indication of just how many people are struggling, but uncomfortable beds aside, there are scores of interwoven reasons people have trouble sleeping. Meir Kryger’s The Mystery of Sleep takes a clinical approach to disentangling some of them.

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