The boundaries between sickness and health are being redrawn.

Mental health categories are shifting and expanding all the time, radically altering what we consider to be ‘normal’. Genetic tests can now detect pathologies decades before people experience symptoms, and sometimes before they’re even born. And increased health screening draws more and more people into believing they are unwell.

An accurate diagnosis can bring greater understanding and of course improved treatment. But many diagnoses aren’t as definitive as we think. And in some cases they risk turning healthy people into patients.

Drawing on the stories of real people, as well as decades of clinical practice and the latest medical research, Dr Suzanne O’Sullivan overturns long held assumptions and transforms how we think about illness and health.

THE MUST-READ SUNDAY TIMES BESTSELLER

A BOOK OF THE YEAR IN THE TIMES, SUNDAY TIMES, FINANCIAL TIMES, GUARDIAN, ECONOMIST, OBSERVER, LONDON STANDARD, NEW STATESMAN AND IRISH TIMES AND A RADIO 4 BOOK OF THE WEEK

‘A brilliant study of the dangers of overdiagnosis’ – GUARDIAN

‘Compassionate and bracingly independent thinking’ – THE TIMES

*As heard on Good Morning Britain, Sky News, Radio 4 Today and more.*

From autism to allergies, ADHD to long Covid, more people are being labelled with medical conditions than ever before. But can a diagnosis do us more harm than good?

A BEST BOOK OF 2025 IN THE TIMES, GUARDIAN, LONDON STANDARD, NEW STATESMAN AND IRISH TIMES

‘Slices through the confusion and the contradictions with grace and compassion. I cannot say good enough things about it.’ – CHRIS VAN TULLEKEN

‘A brilliant study of the dangers of overdiagnosis’ – GUARDIAN, book of the day

‘Be prepared for compassionate and bracingly independent thinking’ – THE TIMES

The boundaries between sickness and health are being redrawn.

Mental health categories are shifting and expanding all the time, radically altering what we consider to be ‘normal’.

Genetic tests can now detect pathologies decades before people experience symptoms, and sometimes before they’re even born.

And increased health screening draws more and more people into believing they are unwell.

An accurate diagnosis can bring greater understanding and of course improved treatment. But many diagnoses aren’t as definitive as we think. And in some cases they risk turning healthy people into patients.

Drawing on the stories of real people, as well as decades of clinical practice and the latest medical research, Dr Suzanne O’Sullivan overturns long held assumptions and reframes how we think about illness and health.

‘To compare any book to a Sacks is unfair, but this one lives up to it . . . I finished it feeling thrillingly unsettled, and wishing there was more.’ – James McConnachie, Sunday Times

In Sweden, refugee children fall asleep for months and years at a time. In upstate New York, high school students develop contagious seizures. In the US Embassy in Cuba, employees complain of headaches and memory loss after hearing strange noises in the night.

These disparate cases are some of the most remarkable diagnostic mysteries of the twenty-first century, as both doctors and scientists have struggled to explain them within the boundaries of medical science and – more crucially – to treat them. What unites them is that they are all examples of a particular type of psychosomatic illness: medical disorders that are influenced as much by the idiosyncratic aspects of individual cultures as they are by human biology.

Inspired by a poignant encounter with the sleeping refugee children of Sweden, Wellcome Prize-winning neurologist Suzanne O’Sullivan travels the world to visit other communities who have also been subject to outbreaks of so-called ‘mystery’ illnesses.

From a derelict post-Soviet mining town in Kazakhstan, to the Mosquito Coast of Nicaragua via an oil town in Texas, to the heart of the Maria Mountains in Colombia, O’Sullivan hears remarkable stories from a fascinating array of people, and attempts to unravel their complex meaning while asking the question: who gets to define what is and what isn’t an illness?

Reminiscent of the work of Oliver Sacks, Stephen Grosz and Henry Marsh, The Sleeping Beauties is a moving and unforgettable scientific investigation with a very human face.

‘A study of diseases that we sometimes say are ‘all in the mind’, and an explanation of how unfair that characterisation is.’ – Tom Whipple, The Times Books of the Year