Jackie, a softly spoken woman in her 70s, had to get rid of her beloved motorbike when she realised she had been driving it while fast asleep – sleep-riding. Adrian, 39, collapses into slumber every time he tells a joke. Don, a tall American in his 60s, has such a problem with eating in his sleep that once, after fitting a padlock to his fridge, he got up to find he had polished off his pet parrot’s bird seed. He feels frustrated that his condition is often treated as “comic relief”; for him and the other patients in Guy Leschziner’s clinic, sleep disorders are no joke.

These are just some of the case histories in The Nocturnal Brain. Leschziner describes himself as a consultant neurologist and sleep physician, but he’s also part detective and part marriage counsellor, as well as a patient listener and a droll storyteller. “I later discover that corks” – in the bed – “are a traditional remedy for night cramps, although I suspect this is not supported by a rich evidence base,” he writes, after interviewing a desperate patient with restless legs syndrome.

One thing common to many of these sleep disorders is that parts of the brain (often those that regulate movement or emotions) can be awake, while others (rational thinking and memory) are asleep. This explains how a dreaming Alex, a twentysomething with “non-REM parasomnias”, jumped on his flatmates at 4am shouting, “Oh, God, did you see that helicopter?”, and then couldn’t remember a thing about it in the morning.

Effective brain imaging is difficult, even now, and Leschziner compares the electroencephalogram (EEG) to using a snorkel and mask to map the floor of the world’s oceans. And it doesn’t help that no patient can explain what happens while they are unconscious. Robert, a “confident and erudite” man in his 70s, is referred to the clinic when his girlfriend reports him saying frightening and abusive things in his sleep. It turns out she is lying. (It surprises me that none of the doctors who examined Robert ever asked for a recording.) But Janice, who grew up in and out of children’s homes, had her choking sensations on falling asleep dismissed as bad behaviour. Now in her 50s, she is finally taking a type of anti-epileptic medication whose effects have been “dramatic”.

Chronic insomnia now affects one in 10 adults. So it’s not surprising that several recent bestsellers have attempted to tell us how to sleep better. Leschziner questions whether an obsession with sleep is helpful, and refers to a new condition, “orthosomnia”, in which “people are diagnosing themselves with sleep disorders based upon the dodgy output of their sleep trackers”. He advocates instead a holistic approach to sleeping better, declaring that mental health and physical health are indivisible. The Nocturnal Brain will not promise to cure your insomnia, but it does make for an entertaining and thought-provoking bedtime read.

• The Nocturnal Brain is published by Simon & Schuster (£16.99). To order a copy go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £15, online orders only. Phone orders min p&p of £1.99.