Equally worrying is that he has occasionally drifted off while walking down the street. ‘I remember not being able to control my eyelids and sort of drifting off, falling asleep. But when I got to the road, and a car – voom!’ – he simulates a car driving past him very close – ‘it suddenly snapped me out of it. I could have walked out in front of that car. A cold reality hit me.’
Christian also used to work on the hovercraft that ran between Dover and Calais, hurtling across the English Channel. I recall taking such a Channel crossing as a child. It was a relatively calm day, but nevertheless I vividly remember the noise and being thrown up and down with every wave, worse than the most turbulent flight I have ever been on. But for Christian, the discomfort of the hovercraft was no problem. ‘I used to just go to sleep. Like pretty much every job I’ve ever had.’
Like Phil and Adrian, Christian also experiences cataplexy. For him, the trigger seems to be mainly laughter. ‘I might watch Fawlty Towers, and John Cleese’ll do something funny and I think it’s the most hilarious thing I’ve ever seen in my life. And that triggers the cataplexy, [affecting] basically all my muscles. My cheeks and my facial muscles go a bit funny. It’s like they’re wobbling. I lose control of my arms and my legs.’
A few years ago, I and a couple of my colleagues tried to record Christian’s cataplexy in an MRI scanner, by playing one of his reliable triggers on a screen while he was inside the machine over and over – the scene from The Office when David Brent shows off his dancing skills to his colleagues, in a buttock-clenchingly awful display of self-delusion and lack of insight. It was a resounding failure, not because we could not trigger the cataplexy, but because of the technical difficulties of combining the scan with a recording of his brainwaves.
And, like Evelyn, Christian also has hypnagogic hallucinations. He will often see dark figures in the room as he drifts off to sleep, but he also has had even more bizarre hallucinations. He has occasional memories of floating above himself, like an out-of-body experience. Christian would also experience something like the descriptions of the incubus or succubus in Chapter 9. ‘I’m not a religious person, but I believed that I was being visited by a succubus, a demon, of a night-time. It was a hallucination of smoke. It wasn’t a demon in a person form or anything. It was like a thick smoke that would come to me.’ He hesitates. ‘In my mind this thing was coming to me, having sex with me, and then leaving. And it would do this every night. I could see the smoke even though I was asleep with my eyes open. I could grab it. Not something sitting on top of me as such, but something sort of entering me – without sounding crude – in a sexual way.’
He adds: ‘I was even ready to go and see a priest, actually just to have a chat with him. But I came to see you first!’ he smiles. I tell him I am a poor substitute for a priest.
I presume the basis of Christian’s narcolepsy, as in Phil and Adrian, is damage to that small area deep in the brain called the lateral hypothalamus. I have never checked his levels of hypocretin, the chemical produced by this region, in his spinal fluid, but I have no doubt that it would be low or even completely absent. The destruction of this tiny nucleus at the very centre of the circuitry that controls our sleep and regulates dreaming is responsible for all his symptoms. The switch that stops him suddenly drifting off to sleep, or keeps him from entering into REM sleep, has gone awry. For most people, our sleep cycles through REM sleep four or five times every night, and we may perhaps remember a dream if we wake in the morning out of REM sleep. But Christian flicks rapidly in and out of sleep, resulting in his sleep attacks at highly inappropriate times, such as behind the wheel of his fork-lift truck or in the baying crowd of a football game. And he goes directly into REM sleep from wake, resulting in these strange and scary hallucinations as he lies in bed.
In addition, this neurological damage results in his REM sleep being unstable, so he judders constantly between REM sleep and wake at night. And it is in the blurred margins between REM sleep and full consciousness throughout his nocturnal hours that he recalls his dreams. Not a fragment of a memory or a story, dimly recalled on waking, but constant, vivid, real, recurring dreams, so intense and colourful that they are sometimes difficult to distinguish from real life. I am fascinated by his descriptions.
Christian dreams of the same four people almost every night. ‘Real people that I went to primary and secondary school with,’ he tells me. ‘These four people that I haven’t seen for maybe twenty years, but they’re in my dreams every night.’ He laughs slightly sheepishly. ‘I’m having a bit of a love affair with one of the girls. Actually two of them!’ He feels the need to clarify: ‘This sounds really dodgy when I say a love affair. The people that I’m actually seeing in my dreams are kids. I’m not having a love affair where I’m an adult and they’re children. I’m the same as them. I’m the child as I was in the past.’
I ask if he is simply reliving old memories, but he is clear that he is living new experiences, almost a new life. ‘One of them used to be a girlfriend of mine, and another one was just a classmate that I quite fancied. So I’m having this really weird love affair that’s actually not happening in reality in any way, shape or form – I mean I haven’t seen them for twenty years! I have seen pictures of them on Facebook, so I do know what they look like as adults, but I don’t dream of them like that because I’ve never interacted with them.’ He leads a separate life at night – a social and romantic one – but he is clear that his relationships do not have a sexual aspect to them. In his dreams, it is a time of innocence, a period of happiness in his life, without worries or concerns.
As well as the content, it is also the intensity of his dreams, and their persistence, despite waking, that is equally arresting. He finds it difficult to describe, and illustrates it with an example.
Say in the dream I’m walking down the road and I meet Fred Bloggs. In the dream I’m saying, ‘Hello, Fred, how’s it going?’ I’m seeing it from my point of view. As soon as I wake up, as soon as my eyes are open, the dream is still going on. But from that point on, I’ve gone from just seeing Fred Bloggs and saying hello to it suddenly being narrated to me. It will suddenly turn into a voice that is reading the book to me. So I’m talking to Fred Bloggs, [then suddenly the dream becomes] ‘Christian’s talking to Fred Bloggs. He shakes his hand.’
My interpretation of this is that aspects of his dream, but not the full dream, are leaching into wakefulness. I ask him what happens when he drifts back to sleep. He says that the dream then simply continues, without the narrative voice. He finds himself back in the street, talking to Fred. ‘The dream just continues seamlessly,’ he replies.
* * *
As I watch my younger daughter in her bed, I am always amazed by – and envious of – the speed with which she falls asleep. One moment, she is pestering yet again for a puppy, a final thought before sleep; the next moment, her eyes are closed, her breathing slows, and she is out like a light. It is as if she has fallen off a cliff, deep into the ocean of sleep, unaware of the external world. The transition is sharp, immediate, sudden. I am sure that she never gives sleep a second thought. It is instinctive, primordial, a biological act, like eating or drinking, something that just happens. She does not consider what sleep is for, other than not feeling sleepy, and has no awareness of herself asleep – with one exception. She is aware that she has dreamt, or has had a nightmare. For most of us, at least those of us for whom sleep is not an issue, dreaming is the only aspect of sleep that percolates into our consciousness. Apart from the physical act of waking up, it is the only evidence that we have actually been asleep. And it has always been like this. Dreaming is an intrinsic part of the human experience, and maybe the experience of other mammals, although of course we cannot ask them. Humans have been puzzling over the meaning or significance of our dreams for time immemorial, and dreams have some part to play in almost every religion.
One of the earliest written texts still in existence is the Egyptian Dream Book, a papyrus document
now housed in the British Museum in London, only forty minutes’ brisk walk from Guy’s Hospital. It is too fragile, too delicate, to remain on display. Exposure to even the low levels of light in a display case risk the pages crumbling to nothing. Dating back to about 1220 BC, it details 108 dreams, categorising them into good and bad, interpreting what these dreams predict. I have been fortunate enough to see these ancient texts for myself.
After being ushered into the ancient Egypt and Sudan study room, four frames of glass are brought out and gently placed on the oak desk in front of me. Sandwiched between the glass plates are the papyri themselves, some mere fragments floating, disconnected, while one papyrus in particular is surprisingly large and intact, about 2ft wide by 1ft high. I can see the feathering of the script in black and red ink, where the scribe’s hand has risen off the page. It is astounding to see something written over 3,000 years ago with ink on papyrus, and to see the marks of its author. To my eye, it actually looks like the work of more than one person, with different-sized symbols. The main text is precise, regularly spaced, but in areas of the documents, a different hand has added to it; larger, more florid, less controlled, like comments in a margin. And, although hieroglyphics is not my strong point, I can make out what I take to be a list, each sentence or phrase marked by a red symbol that I presume to be a bed. I wonder if each item is one of the dreams and their interpretation.
The ancient Egyptians believed that their gods could show themselves to us in dreams, and that dreams could also serve as a window into the netherworld. Similarly, Joseph, in the Book of Genesis, predicted seven years of feast followed by seven years of famine by interpreting the dreams of Pharaoh. In Kabbalah, a branch of Jewish mysticism, it is believed that, in sleep, fifty-nine out of the sixty parts of our soul leave us, with one-sixtieth left behind to sustain us – one-sixtieth being seen as the smallest detectable amount of anything. While our souls enter the spiritual realm to be nourished, glimpses of events coming our way trickle down into our bodies, taking the form of dreams.
Few people would now consider dreaming to be a prediction of the future, but the answer to the question, ‘Why do we dream?’ is a resounding, ‘I don’t know.’ If you think about it, this is staggering. Something that is fundamental to the human experience, that we all do on a nightly basis, much like eating and drinking, remains a mystery. The concept of asking ‘Why do we eat?’ and being answered ‘I don’t know’ is totally preposterous.
We consider REM sleep and dreaming to be the same thing, but as I have already said in Chapters 2 and 3, we know that this is incorrect. We know that if you wake someone up in non-REM sleep, they will often describe dreamlike phenomena, but it seems that REM sleep is most closely correlated with those dreams of narrative structure, of a plot evolving in your mind, a story that unfolds. But REM sleep and this type of dreaming are clearly not precisely the same thing. REM sleep is defined as the state of sleep during which your body is paralysed but your brain is very active. The EEG, the electrical signals that give us a limited insight into brain activity, looks remarkably similar to the awake brain, but the only muscles moving are those that allow us to breathe, and those that move our eyes. REM sleep is also a feature of brain activity that starts in the womb. In fact, as we enter the third trimester of our development, almost all our time is spent in that brain state, at least in premature babies born at this stage. And, even after birth, a third of each 24-hour period is spent in REM sleep.
As Meir Kryger, professor of sleep medicine at Yale, told me when we were discussing this: ‘What in the world can babies be dreaming of?’ The answer is probably nothing, or at least nothing like what we know of as dreams. It seems likely that our experience of dreaming, in the way we understand dreams, only really begins at an age when the brain is developed enough to represent subjective experience in a narrative way. What I mean by this is that our brains can only understand our experiences of life, and put them together in a story-like way, when they reach a particular stage of maturity and organisation. And the age at which our dreams coalesce into what we recognise to be dreams is probably somewhere around five years old, although it is difficult to ascertain. It is difficult enough to understand why your two-year-old is having a tantrum, never mind interrogating them as to their dream experiences, and certainly young children will wake up and say they have had a bad dream.
But, as Kryger alludes to, how can a foetus at twenty-eight weeks old dream of life experiences, if it has no experience of anything outside the womb? Allan Hobson, professor of psychiatry and sleep medicine at Harvard, has proposed that this ‘dreamless REM sleep’ is fundamental to the development of consciousness, what he has termed ‘protoconsciousness’. Our behaviours in infancy and childhood, which start out as unconscious automatic actions – crying for food, suckling, reaching for objects without any self-awareness or volition – gradually become what we perceive to be conscious, through rehearsal and ‘practice’ in a virtual space. He argues that REM sleep is a driver of the emergence of secondary consciousness – that is the degree of consciousness that differentiates us from other species, namely volition, self-awareness, reasoning, insight, abstract thinking – from primary consciousness, simple perception and emotion that other mammals experience. Hobson says, ‘I think protoconsciousness is an unfortunate term which I used, now with some embarrassment. But I think that what I am trying to get across is very simple – that the brain development that leads to consciousness occurs very early, it occurs in pregnancy.’
However, while REM sleep is a brain state – measurable and detectable – dreaming is a subjective psychological state. At least we have some sort of correlate of dreaming in REM sleep, something that is easy to determine and study. So let’s set dreaming aside for a while and concentrate on REM sleep. What do we know about its function? Well, if we spend very high proportions of our time in it as our brains develop, in the womb and in childhood, perhaps it has a role in promoting that development. But REM sleep persists throughout our lives, into old age, so this cannot be the whole story. Maybe it also has a role in the ongoing maintenance and reconstruction of our brain? Perhaps REM sleep allows us to practise or prepare for waking life, allowing us to sleep and fine-tune our brains for when we wake. Jouvet, he of the cats with lesioned brains that appeared to act out hunting or fighting in REM sleep, proposed that REM sleep allowed the rehearsal of instinctive behaviours crucial to survival. Others have pointed out that REM sleep in kittens drops off markedly as soon as they open their eyes, suggesting that REM sleep somehow prepares certain circuits in the brain for future functions or activities.
An alternative theory regarding the function of REM sleep is that it is fundamental to the regulation of mood and one’s psychological state. While initial studies disrupting the REM sleep of human subjects showed that, after a few days, people began to experience significant problems with mood, other studies have since pointed to REM and non-REM sleep being equally important. To confound matters, a single night of preventing REM sleep in people who are depressed can cause marked improvement of mood, and older antidepressant drugs can completely abolish REM sleep. So this is not an entirely convincing theory either.
What about as a facilitator of learning and memory? Certainly, a common finding from animal studies is that REM sleep is prolonged after learning a new task, and that disruption of REM sleep also disrupts the learning process. The evidence from human studies is for the most part weak, however, and if there is such an effect, it must be relatively minor. So, maybe REM sleep is not only about storing new material, but also about maintaining what we already know. Perhaps REM sleep triggers circuits that encode memories or skills, reinforcing them and preventing us from forgetting them. Evidence certainly points towards REM sleep being fundamental to a range of aspects of learning and skills. Matthew Walker, one of the foremost researchers in this field, and his colleagues have shown that important abilities like recognising the emotions expressed by faces, maze navigation and creative thinking ar
e all facilitated by REM sleep. Creativity and dreaming have long been linked. The examples of Mary Shelley dreaming up scenes from Frankenstein, Keith Richards and the opening bars to ‘Satisfaction’, Mendeleev conceiving of the periodic table and Paul McCartney composing ‘Yesterday’ are often invoked. So, maybe REM sleep has the power to coalesce multiple memories, disparate experiences, and integrate them into a work of genius.
One peculiarity of REM sleep is that, unlike every other moment of our lives, the mechanisms that regulate our body temperature fail us. While for the rest of the time our body temperature is kept absolutely stable, in REM, it drops. This is actually a highly dangerous state for us to be in. Even small fluctuations in temperature can result in our brains not working properly, or heart rhythm abnormalities. I will occasionally see patients in the intensive-care unit rendered comatose through hypothermia, or with brain damage resulting from overheating due to recreational drug use. Given that the loss of temperature control is so hazardous, it seems a high price to pay, especially as we enter this state multiple times every night. Evolution is no fool, and this implies that REM sleep, and this loss of our internal thermostat, must have a crucial function.
There is a safety cut-off, however: if we are cold, we will not enter into REM sleep. It seems that if we are not warm, the brain will not risk losing control of heat regulation. But there is a paradox here: if rats are prevented from having REM sleep, they soon lose the ability to regulate their body temperature, and soon die as a result. Hobson, when I speak to him on the telephone, likens this to his wife. ‘My wife’, he tells me, ‘is a neurologist too. She always feels cold in a room that everyone else feels is hot. This is because she is always sleep-deprived; she works too hard!’ So, if REM sleep is important for the regulation of our body temperature, how does this fit with us losing this control while we are in REM sleep? I ask Hobson what he thinks of this apparent paradox. ‘When we go into REM sleep, we are fixing the system that regulates our body temperature. It’s like when you take a car to the shop [mechanic], you run the car with the wheels off the ground. You stop it working normally to fix it.’ So, maybe by taking the system that maintains us at a steady 37°C offline, it provides an opportunity to tweak the system, to maintain it and keep it in good running order.
The Nocturnal Brain Page 25