The Nocturnal Brain Read online

  For Ava, Maya and Kavita. Also for Heinz, who always wanted to be a doctor – history intervened.

  CONTENTS

  Introduction

  1 Greenwich Mean Time

  2 In the Still of the Night

  3 Disney Was Right

  4 Rumblings

  5 The Sleep-Talking Bus Driver

  6 Weak With Laughter

  7 Buzzing Bees

  8 Seized by the Throat

  9 Floating Eyeballs

  10 Jekyll and Hyde

  11 The Waking Effects of Coffee

  12 A Peculiar Fairy Tale

  13 Inception

  14 Losing Sleep

  Epilogue: Some General Thoughts on Sleep

  Appendix of Diagrams

  Acknowledgements

  Glossary

  Further Reading

  Index

  INTRODUCTION

  We think of sleep as a tranquil act, when our minds are stilled and our brains are quiet. The act of sleeping is a passive one, and is associated with a blissful unconsciousness and the delight of waking refreshed. The only awareness we might have of something happening in the night are the fragments of a dream. That is, at least, for most of us. But for many of the patients in my sleep clinic, their nights are anything but this. Rather, a night in the sleep laboratory, where I admit my patients to study their nocturnal behaviour, is punctuated by shouts, jerks, snores, twitches or even more dramatic goings-on, and the torture of poor or even no sleep at all.

  The normal expectation of waking up feeling ready for the day ahead is rarely found among my patients, or indeed their partners. Their nights are tormented by a range of conditions, such as terrifying nocturnal hallucinations, sleep paralysis, acting out their dreams or debilitating insomnia. The array of activities in sleep reflects the spectrum of human behaviour in our waking lives. Sometimes these medical problems have a biological explanation, at other times a psychological one, and the focus of the clinical work that I and my colleagues do is to unravel the causes for their sleep disorders and attempt to find a treatment or cure.

  For the past few years, I have seen hundreds of patients per year with sleep disorders, causing insomnia, profound excessive daytime sleepiness or bizarre and frightening experiences at night. My path to this work has been accidental. In keeping with most doctors of my generation, my exposure to the world of sleep during my medical degree was pretty much non-existent. I cannot recall a single moment of teaching that focused on sleep until well into my clinical training as a neurologist, almost a decade after I graduated. It was only by chance, when I opted for an intercalated degree in neuroscience as a nineteen-year-old, that I was asked to write an essay on the function of sleep. As a naive but intellectually curious teenager, I had assumed, like most people, that the function of sleep was to stop you feeling sleepy, and that assumption was born out of personal experience. I went to bed when sleepy, and when I woke up, that sleepiness had left me.

  However, in preparation for that essay, I came across a paper co-authored by Francis Crick, one of the discoverers of the structure of DNA. Crick had in later life become increasingly fascinated by consciousness and neuroscience, in part driven by a sabbatical at the Salk Institute in San Diego, a world-leading centre in neuroscience research. In that paper, Crick and his colleague speculated as to the function of dreaming, which at that time was thought to exclusively happen during a stage of sleep known as rapid eye movement (REM) sleep. They argued that the function of dreaming, rather than representing a Freudian ‘royal road to the unconscious’, was a form of housekeeping for the brain. Dreaming, they postulated, acts to prune out connections between cells in the brain that have developed during the day, and constitutes a type of ‘reverse learning’ to get rid of useless information. The validity of this hypothesis remains controversial, but reading this paper was a light-bulb moment for an ignorant but interested medical student. The realisation that sleep not only had a purpose other than making you feel less sleepy, but was also a complex set of brain states, not simply a state of unconsciousness between going to bed and waking up, had a profound effect. It sparked my interest in sleep and its disorders, and has led me into this fascinating and often bizarre clinical realm of sleep medicine.

  In this twilight world, glitches in the human brain result in striking and poorly understood conditions. All the more so as, in contrast to chest pain, headaches, skin rashes and more usual medical symptoms, these problems most often arise without any awareness, at a time when people’s brains and minds are detached from their internal and external world.

  In the pages that follow, I will introduce you to some of my patients who have been willing to share their stories. The tales of these individuals are dramatic, terrifying, illuminating, poignant and sometimes amusing. You will see how their disorders affect the lives of those around them, their relationships with partners and children, as well as their own.

  So why is it that I’m writing about these patients? And, more importantly, why should you read about them? Many of the stories that follow are about patients with extreme sleep disorders, at the very limits of the spectrum of human experience, and it is by studying these extremes that we can learn about the less severe end of the spectrum; by understanding how these patients are affected by their sleep disorders, we come to know a little about how we ourselves are affected by our sleep. Many of these conditions are not rare, either: chronic insomnia affects one in ten adults; sleep apnoea about one in fifteen; and restless legs syndrome (RLS) about one in twenty. It is almost certain that anyone reading this book will either suffer from one or more of these disorders themselves or know someone close to them who does.

  * * *

  Doctors love stories; we love telling them and we love hearing them. We teach, learn and entertain each other with stories. In medical parlance, what a patient tells you in their own words is the history, the story, of their problem. As medical students and junior doctors, we acquire the skills to extract this history. Our medical journals and conferences are full of case histories, and it is precisely through the sharing of these stories that we circulate expertise and further our knowledge base.

  I am a neurologist first and foremost, and the skills that I have learned through my neurological training are equally applicable in the practice of sleep medicine. As registrars (the equivalent of senior residents in the US) at the National Hospital for Neurology, Queen Square, in central London, we were exposed to a rite of passage: the venerated Gowers Round on a Thursday afternoon. Largely for teaching purposes, but also to provide some entertainment, this session takes place in a large lecture theatre with steep stalls. From the second row, where the neurology registrars sat, it felt a little like being in one of the amphitheatres of Rome – and we were about to be fed to the lions. The craftiest registrars among us would find a patient that urgently needed assessment on the wards so that they could creep into the rear of the auditorium late, along with the hordes of junior doctors, medical students and visiting neurologists from abroad. The most devious would arrange for a colleague to page them early in the proceedings so they could make a show of leaving to deal with ‘an emergency’ before sneaking in at the back of the lecture theatre later on.

  The audience would await the sporting event with gleeful anticipation, while the registrars could only hope to survive the ordeal with a shred of dignity left intact. I have heard stories of colleagues vomiting in nervousness every Thursday lunchtime, others taking a beta-blocker pill to calm their anxiety prior to entering. For a painful ninety minutes, three cases would be presented. Usually the patients would be wheeled in at the front and the consultant chairing Gowers that day would grill the registrars on the cases, often exposing gaping holes in our knowledg
e under the glare of the 200 people sitting behind us.

  After a particularly humiliating session, you would feel 400 eyes burning into the back of your head, as you wished that the earth would open up and swallow you whole. Some of my colleagues still talk about their most painful experiences twenty years later, such is the impact. (Even writing about it now I feel a slight flush, a delicate churning in the stomach . . .) As excruciating as these rounds were, they provided a fantastic opportunity to learn and to see conditions that you might never have heard of before, the knowledge perhaps reinforced by the sheer terror of the lesson. (I myself shall remember Triple-A syndrome and its association with neurological problems until my dying days, even though I have never heard it even mentioned since.)

  While the fear of total humiliation in the Gowers Round sharpens the mind, it is hearing the complex stories of these patients that is its most valuable aspect. It is the patient history that physicians in general and neurologists in particular fixate upon, and the same can be said in sleep medicine. By far the most useful information when making or ‘formulating’ a diagnosis is the history, not the examination or the results of blood tests or scans. A man’s recollection of some twitching in the left hand just before he fell and injured his head, suggesting a seizure arising in the right motor area of the brain, which leads to the diagnosis of a brain tumour; a young woman who reports visual loss spreading slowly over minutes across the visual field, confirming the visual aura of migraine – the spread of abnormal electrical activity associated with migraine headaches across the visual cortex – rather than an eye problem; the episode of dizziness several years previously that suggests that the woman sitting in front of you with a tingly hand may have multiple sclerosis rather than nerve impingement in the wrist; or the family history of imbalance, implying that the man with heavy alcohol use might have coordination difficulties due to a genetic disorder rather than as a result of his excessive drinking. The best neurologists I have worked with are the ones who have the patience and the ruthless determination to extract the full history, like a forensic FBI interrogator.

  Such is the focus on the use of case histories for teaching that the case presentation is the standard way in which doctors are trained and their expertise is maintained. It enables us to ‘experience’ rare cases that we may at some point see in the future – hence the Gowers Round and its variations that exist in hospitals throughout the world.

  During an admission into hospital, most patients are frustrated by the repetitive ‘taking’ of their history by medical students, tiers of junior doctors, generalists, specialty teams and consultants. The history is regurgitated and pored over again and again, and various aspects are repeatedly explored further. The impact of the condition on various aspects of one’s life are surveyed but, as a rule, this facet of our patients’ stories is something we do less well in the melee of a busy outpatient clinic, with the number of patients waiting outside our door ever increasing, under the irritated stares of people who have been waiting way beyond their appointment times. Our understanding of their relationship with their condition, how it affects their social or family life, and the minutiae of their complaints that are irrelevant to moving forward in the management of their illness are bystander casualties to efficiency. In reality, we simply try to extract all the necessary information to make a firm diagnosis and to formulate a treatment plan in the minimum possible time, so that we can move on to the next person.

  As a schoolboy, I vividly remember picking up a copy of Oliver Sacks’s book, The Man Who Mistook His Wife for a Hat. As I read these stories of a mariner unable to form new memories, of a man who could not recognise his own leg, of the woman who heard music as a result of epileptic seizures, I was gripped. But it was the context in which he put these symptoms, the impact on the lives of the human beings in front of him, that led to a deeper understanding of the nature of these conditions and how they affect us. And it was reading these stories that inspired my interest in neuroscience, and no doubt many of my colleagues too.

  * * *

  Neurologists are obsessed by ‘lesions’, the medical term for damage or injury. Whenever we assess a patient, we ask ourselves where the lesion is. We put together the symptoms and signs to ‘localise the lesion’, to identify its location in the nervous system. The damage may be due to a stroke, an injury, or a tumour. It may be visible to the naked eye or evident on a scan. It may be microscopic, only detectable after a biopsy or postmortem. Or it might be transient, a ‘lesion’ that results from the temporary dysfunction of a small part of the nervous system due to an electrical aberration. But it is not just numbness of the arm or paralysis of the face that can be understood in terms of a lesion. Many of the sleep disorders that you will hear about in the following chapters are also a direct result of lesions.

  Perhaps the most famous lesion of all in the world of neurology affected the brain of a man called Phineas Gage. Born in Grafton County, New Hampshire, Gage began working with explosives in his youth, perhaps on farms or nearby quarries. His introduction to blasting powder turned out to be very unfortunate for him, but very fortunate for modern neurology. At around 4.30 p.m. on 13 September 1848, near Cavendish, Vermont, while managing a work gang blasting rock to build a local railroad, the 25-year-old Gage was tamping explosive into a hole with a tamping iron, a long metal pole designed to pack explosive tightly. As he pushed it down, it must have sparked against the rock, igniting the explosive in the hole. The tamping iron flew out of the hole like a spear, whereupon it impaled Gage, entering the left side of his face, passing behind his left eye and smashing through the front of his brain and the top of his skull. The javelin-like rod landed some distance away, ‘smeared in blood and brain’. Extraordinarily, after a brief convulsion, he sat up and was taken to the local doctor in an oxcart. According to this doctor’s gruesome account,

  I first noticed the wound upon the head before I alighted from my carriage, the pulsations of the brain being very distinct. The top of the head appeared somewhat like an inverted funnel, as if some wedge-shaped body had passed from below upward. Mr Gage, during the time I was examining this wound, was relating the manner in which he was injured to the bystanders. I did not believe Mr Gage’s statement at that time, but thought he was deceived. Mr Gage persisted in saying that the bar went through his head. Mr G. got up and vomited; the effort of vomiting pressed out about half a teacupful of the brain, which fell upon the floor.

  Gage’s survival, especially in the mid-nineteenth century, was truly remarkable. But even more so was the change that occurred in him after the accident. After a long convalescence, complicated by delirium, infection and coma, he finally made it to his parents’ home some ten weeks later. It was not the same man who returned, however.

  The details are scant, but prior to his accident he was described as hardworking, diligent and popular. His employers praised him as ‘the most efficient and capable foreman in their employ’. After that dreadful accident, though, Harlow, one of his physicians, wrote,

  The equilibrium or balance, so to speak, between his intellectual faculties and animal propensities, seems to have been destroyed. He is fitful, irreverent, indulging at times in the grossest profanity (which was not previously his custom), manifesting but little deference for his fellows, impatient of restraint or advice when it conflicts with his desires, at times pertinaciously obstinate, yet capricious and vacillating, devising many plans of future operations, which are no sooner arranged than they are abandoned in turn for others appearing more feasible. A child in his intellectual capacity and manifestations, he has the animal passions of a strong man. Previous to his injury, although untrained in the schools, he possessed a well-balanced mind, and was looked upon by those who knew him as a shrewd, smart business man, very energetic and persistent in executing all his plans of operation. In this regard his mind was radically changed, so decidedly that his friends and acquaintances said he was ‘no longer Gage’.

  It seems that what had on
ce been a pleasant, social man had been replaced with a belligerent, swearing and unpleasant character: ‘He was gross, profane, coarse, and vulgar, to such a degree that his society was intolerable to decent people.’ The story of Gage took on a life of its own, and was no doubt exaggerated and overblown with repetitive telling. In reality, it appears that in later life he was left less affected. But his was certainly one of the most famous historical cases of localisation, illustrating that different parts of the brain have different functions. damage to the frontal lobes, whether through tumour, types of dementia or tamping iron, is known to cause personality change, and suggests that the frontal lobes have a fundamental role in our social behaviour and planning.

  Correlating lesions to symptoms or signs, therefore, allows us to understand how our brains function, how they are organised and how our lives are determined by them. These lesions may be accidental or caused by disease. In animal experiments, they may be created by design. In clinical practice, we endeavour to characterise the location of the lesion in the nervous system. We attempt to form a unifying diagnosis, a single underlying cause to explain all the symptoms and examination findings.

  In the world of sleep, however, this principle of Occam’s razor – that the simplest explanation, a single diagnosis, should be sought to explain everything – does not always apply. Of course, in the neurology clinic, the explanation for a patient’s migraine may be influenced by their stress levels or whether they have drunk alcohol, but for the most part this does not alter the diagnosis. In contrast, however, as anyone will testify, sleep is the absolute confluence of factors biological, social, environmental and psychological. Clearly anxiety may cause the tingling in your hands, and noise may worsen your migraine, but the link between your snoring, your work shift pattern, your noisy bedroom, your anxiety and your experience of sleep is so much more direct; these factors so much more fundamental to the difference between feeling rested and alert or exhausted beyond belief. Understanding all these aspects of your life is crucial to the evaluation of your sleep. But exploring all these facets can be a challenge in a thirty-minute consultation, especially when you are taking notes, struggling with the computer and dictating a letter at the same time.