In the 1890s, Ivan Pavlov, a Russian scientist, began experimenting on dogs. He had noticed that his dogs began salivating whenever he came into the room, in expectation of food. He noted that while salivation in response to food is a hardwired response, the association of him with food must have been learned. He then began to train his dogs to associate a bell being rung with the presentation of food, and rapidly his dogs began to salivate at the mere sound of the bell. This phenomenon is termed conditioning, a learned response, and humans are in some ways no different from Pavlov’s dogs, in that we are also subject to conditioning. For example, think of a drink or food that in the past has made you ill. It is likely that even the sight of that food or drink now makes you feel nauseated, perhaps even the mention of it. Conditioning also applies to sleep, however.
If you have no problems with sleep, you associate your bedroom with feeling sleepy, that comforting sensation of slipping under the duvet, putting your head on the pillow, and that wave of relaxation as you drift off to sleep. For the insomniac, the conditioned response is very different. The bedroom is a location of stress and anxiety, dread of the night ahead. The bed itself is a cause of mental or physical hyperarousal, making sleep even more difficult. As Claire says: ‘It [my bed] is a place of misery and a chamber of torture now.’
At the core of CBTi is the breaking down of this negative conditioned response to one’s bed, and rebuilding a positive association. The trick is to once again establish the bed as a sanctuary rather than a torture chamber. This is done by a number of ways. The first is by a rigid regime to avoid you lying in bed at night for prolonged periods while awake, forcing you to leave the bedroom after a few minutes of struggling to get to sleep, and to avoid using the bedroom for anything other than sleep. The second initially sounds counterintuitive. After all, the last thing an insomniac wants is to be sleep-deprived. But what many people with insomnia do is compensate for their poor sleep by spending more time in bed. And what that achieves is to increase the time they are in bed not asleep, thus strengthening the negative conditioned response. So, by limiting the time allowed in bed to five or so hours for a period of a couple of weeks, this builds the brain’s drive to sleep. Like Claire hitting 3 or 4 a.m., eventually the sleep deprivation overrides the hyperarousal state and sleep ensues. This is a crucial step in rebuilding the association between bed and sleep.
At its most extreme, sleep deprivation as a treatment for insomnia has been developed in Australia into an experimental technique called intensive sleep retraining. The patient is asked to stay in bed no more than five hours the night before they come into the sleep laboratory. At 10.30 in the evening, the protocol commences. For the next twenty-four hours, every thirty minutes the patient is allowed to try to go to sleep, with electrodes attached to their scalp. After twenty minutes, if they do not fall asleep, they are asked to get up. But if they do fall asleep, as proven by their brainwaves, after three consecutive minutes of sleep they are woken. By the end of the 24-hour period, they have had forty-eight opportunities to fall asleep. In theory, by the end of the protocol, they are so sleep-deprived that they fall asleep as soon as they are allowed. The conditioned response between bed and sleep has been reestablished. This technique sounds like something straight out of Guantanamo Bay, but results from trials have been impressive. This short sharp shock rapidly reconditions the response to getting into bed, and results in quick improvements in sleep.
CBTi uses similar principles, but in a less brutal manner, and is combined with other techniques to induce relaxation and address hyperarousal, as well as the teaching of good sleep hygiene, the term for behaviours surrounding sleep such as avoidance of bright light and caffeine, and adequate wind-down periods. The results of CBTi are equally good. The improvement in sleep in the short term is equivalent or even superior to hypnotic drugs, and the benefits have been shown to persist for up to three years.
As a result, CBTi is usually recommended as the first-line treatment for insomnia, sometimes in combination with medication in the short or medium term. CBTi can also be used to help the gradual withdrawal of long-term drugs for sleep.
When Claire and I discuss treatment options for her ongoing insomnia, we decide to go down this route of treatment, avoiding adding in further medications in the first instance. The response is quite remarkable. We meet a few weeks after starting CBTi. ‘I was sceptical because I’d tried so many things,’ she admits. ‘I was very up for drug help. I just didn’t believe that anyone could help me.’ She has seen the sleep therapist twice now, and is following the CBTi programme to the letter. She is now spending no more than seven hours in bed.
I count the minutes until eleven o’clock because it’s so hard to stay up and I’m desperately sleepy. I’m waiting. I have my wind-down time. I spend an hour running a bath and lighting candles. And then in the morning the alarm goes at six and I have to get out of bed immediately. I go straight downstairs and I sit there feeling a bit sorry for myself. And I’ve done that every day religiously for three weeks. And it’s got better and better and better. I almost can’t believe that this is happening, but I’m sleeping. The switch [into sleep] seems to be re-emerging!
It is almost too good to be true, and both the sleep therapist and I are cautious not to be overoptimistic. But Claire feels transformed. ‘I almost can’t remember the last time I felt this human. Full of energy and able to concentrate. I feel so excited by what life now holds,’ Claire continues. And, despite my reservations, Claire continues with the rigid CBTi programme for three months, during which her insomnia is held at bay. With improvements in sleep, her restless legs also ameliorate.
The next few months, however, are rocky. For no obvious reason, she suddenly has a resurgence of her anxiety, and her sleep deteriorates again. She ascribes this to a loss of discipline with her sleep programme, but I am not so convinced. I think this is part of her tendency to have incredibly high expectations of herself, to take responsibility for everything around her and her reluctance to accept that she does not have control over everything in her life. We up the dose of her medication for her depression and anxiety, and I suggest we try again to address her psychological difficulties through a clinical psychologist. And, slowly but surely, she gets better. With the clinical psychologist, she recognises patterns of behaviour and thinking that place her under undue stress, pressures that she creates for herself, negative thoughts about her life and her achievements. By recognising these destructive thought processes, she has learned to lessen the emotional consequences of minor events in her life that previously would have triggered profound stress. She has also found a complementary therapist who has helped.
When I talk to her some nine months after we first met, she tells me she is ‘fabulous’. Her anxiety and mood issues have lessened, and she is sleeping regularly. When her head hits the pillow, she drifts off to sleep. Without medication. She is still on a low-dose antidepressant, but is even reducing this gradually. For the first time in five years, she feels normal.
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Ask anyone with insomnia what sleep means to them, and the importance of sleep is immediately obvious. It affects every aspect of our waking lives – mood, energy levels, cognition, memory, immune system, metabolism, appetite, anxiety levels. It influences our relationship with everyone around us, and with ourselves. As Claire says: ‘Sleep changes everything. Without it, no one can function. You can try for a bit, but it gets to the point where you actually start shutting down. I felt like my body was shutting down and my brain was shutting down. And suddenly, with sleep, it’s all opening up again.’
EPILOGUE
SOME GENERAL THOUGHTS ON SLEEP
You can survive longer without food than without sleep. The fact that sleep is fundamental to life is unarguable, but in modern society, at least until recently, we have taken for granted that sleep simply happens, and is a necessary evil to allow us to live our waking lives. Recently, however, largely through the efforts of many of my colleagues aroun
d the world, there has been a shift in how we view sleep. Rather than being a hindrance to our working and social lives, a biological process that keeps us from being productive, the concept of the importance of sleep is percolating through. Its role in the maintenance of our physical and mental health, our sporting prowess, our cognitive abilities, even in our happiness, is slowly being appreciated. And rightly so. People are taking sleep seriously.
We have moved a long way from the Egyptian Dream Book, and indeed from Freud’s Interpretation of Dreams. Freud of course was not even aware of the existence of REM sleep, discovered half a century later, but our understanding of sleep and its disorders, even in the past fifty years, has exploded. There is an apocryphal-sounding but true story of the inventor of CPAP – the technique used to treat sleep apnoea – being invited from Australia to Edinburgh in the 1970s to give a keynote lecture at a conference. At the end of his talk, the professor of medicine at Edinburgh stood up and announced to the audience, composed of the great and the good of the UK medical establishment, that sleep apnoea did not exist in ‘this country’, and perhaps ‘we have exported it all to the colonies’. The eminent Australian physician was so shocked and insulted that he did not return to the UK for some twenty years.
Nowadays, such a statement would be unthinkable, even by the most medically ignorant. And the column by the general practitioner published by the British Medical Journal in 2013, in which he stated that restless legs syndrome was a condition made up by pharmaceutical companies to flog drugs, would, I hope, not be published today. We have moved away from sleep and dreaming being a spiritual phenomenon to one firmly rooted in the physical realm, with an underlying neurological basis. We have fundamentally understood that sleep disorders derive from neurological, psychiatric and respiratory dysfunction, rather than God, witchcraft or lunacy. And we strongly grasp the necessity of sleep in the regulation of neurological, psychological and cardiovascular health.
This shift has driven, and also been driven by, the view that sleep medicine is a multidisciplinary field, requiring the involvement of neurologists, respiratory physicians, psychiatrists, cardiologists, psychologists, ear, nose and throat surgeons, and dentists. And that sleep research necessitates scientists specialised in all these fields.
Technological advances in studying sleep have also been crucial to this scientific progress. It started with the EEG in defining the different stages of sleep, but we now have ways of measuring airflow, chest movements, body movements. We have the ability to image the brain, not only its structure but also its function, using techniques like functional MRI, and radioisotope-based scans like PET and SPECT. We can analyse electrical activity deep within the brain, through implanted electrodes. We can monitor fluctuations in hormones, genes, proteins and metabolites over a 24-hour cycle. We have laboratory techniques that can switch genes off and on simply by shining a light on a section of brain. We can breed mice with manipulated genes, and we can study the genomes of huge numbers of people, looking at common genetic variants and their association with different facets of sleep and its disorders. We can relatively cheaply unravel the genetic code of an individual, identifying each distinct position in the 3-billion-long sequence of letters that comprise the human genome, finding rare mutations that cause disease. Many of these tools now at our disposal were totally unimaginable only a few years ago.
* * *
Two of the most frequently asked questions I hear in my sleep clinic are, ‘How much sleep is enough?’ and ‘What do you think of my sleep tracker?’ With regard to the first question, I do not answer it, at least not with a number of hours. Indeed, I cannot answer it in that way. The question is similar to ‘What is the normal height for a ten-year-old?’ If I look at my daughter’s class photo, the children range in height hugely, but all of them are normal. Likewise, there is a range of normal sleep requirements. It depends on your genes, and the quality of your sleep. The right amount of sleep is the number of hours needed for you to wake up feeling refreshed, not sleepy during the day, but then ready for bed at a regular time, without difficulty dropping off. If you are achieving that regularly, if you are waking up before your alarm, and not catching up on sleep when you have the chance at the weekend, then you are getting the right number of hours’ sleep.
As to the second question, I usually tread delicately for fear of offending. We live in an age where everything needs to be measured. We constantly feel the necessity to apply metrics to our lives, be it how many steps we take, how many Instagram followers we have, how much we earn, how many calories we consume, and of course how much sleep we get. But I do wonder if this tracking of our sleep quantity is helpful. If you meet the criteria above, i.e. have sufficient sleep to function properly during the day without feeling sleepy, then the likelihood is you are getting enough sleep. If you feel tired and unrefreshed, you probably are not, and don’t need a sleep tracker to tell you this. But, apart from just wasting some money on the gadget, there are other potential downsides. These devices are at present relatively inaccurate. Apply five different trackers to your arm and you will get five widely diverging estimates of your sleep duration. They measure movement, not sleep, and depending on the algorithm, give an inaccurate measure of sleep of varying degrees.
Where they could help is if they can prove that your insomnia is related to sleep state misperception, that your experience of insomnia is not borne out by limited sleep overnight. That, however, requires the data to be reliable, for you to trust that the device you are wearing gives a very accurate picture of your sleep. And there is a further issue. If you are already worried about your sleep because you have insomnia, then constantly tracking your sleep can exacerbate these worries – can intensify your obsession with your sleep, and thus make the problem worse. This phenomenon now has a term – ‘orthosomnia’ – where people are diagnosing themselves with sleep disorders based upon the dodgy output of their sleep trackers. For most people, sleep is a subjective experience, and insomnia is most often associated with a normal sleep duration, so your sleep tracker telling you that you have light sleep when you expect deep sleep can in itself have profound effects on your own perception of your sleep.
This does not mean that these devices are totally devoid of value. They can track improvements or deteriorations in sleep with interventions like cognitive behavioural therapy for insomnia, and perhaps most importantly can provide researchers with ‘big data’ on sleep patterns, where the noise of an imperfect technique to quantify sleep is diluted out as a result of huge numbers of individuals. But for the individual person, especially those sitting in front of me in my sleep clinic, I have my doubts. The obsession with the number of hours in bed, with inaccurate measures, results in us overlooking what I have shown in the pages of this book: that there are many factors – biological, psychological, behavioural, environmental – that all influence sleep quality as well as sleep quantity.
It is also important to stress that most studies looking at relationships between sleep and physical and mental health are imperfect. If there is one thing that is very obvious from hearing some of the stories I have told you, it is that we are often unreliable witnesses to our own sleep. Our perception of our night-time and the reality are often entirely different. One of the major problems with performing these studies is that for the most part we rely on what subjects within these studies tell us. Performing sleep studies on everyone is inordinately expensive and practically impossible, at least using currently available technologies. So when we look at large populations, and correlate sleep factors with high blood pressure, heart disease, Alzheimer’s disease and so on, it is likely that a group labelled with insomnia or sleep deprivation is a mixed bag. If we take the example of insomnia, some will have a normal sleep duration, others will have a short sleep duration, some will be on medication causing their insomnia and yet more will have sleeplessness due to the pain or breathlessness caused by medical problems. When correlating sleep duration to mortality, although we try to ad
just for known factors, it is almost entirely impossible to adjust for everything, or to be sure that everyone reporting a sleep time of over seven hours actually is sleeping that amount.
Please don’t misunderstand me: I do not for a second doubt that sleep problems have really major consequences on our physical and mental health. I just believe that there are subtleties there that we have yet to fully appreciate, nuances that we have not yet uncovered. Perhaps as the technologies available to us improve, and we can track sleep rather than movement in the long term, these intricacies will become clearer.
There is another important message in this book. The days when I drifted off to sleep as soon as I closed my eyes are long gone. More usually, as my head hits the pillow, thoughts of papers or lectures I need to write, letters unwritten, patients to call, meetings to arrange, enter my mind. But occasionally I see my narcolepsy patients sitting in my clinic, one minute chatting about their condition, the next minute fast asleep. And when I put my younger daughter to bed, it is like a light switch suddenly turned off. Looking at her and my patients, it is obvious why we think of wake and sleep as entirely different states of existence, with clear borders: a reinforced concrete barrier, the Berlin Wall separating the East of sleep from the West of wake. But this seemingly stark divide belies the incredibly complex choreographed dance of brain nuclei, neurones and circuits, working synergistically and antagonistically to mediate our levels of engagement with our external and internal world that define our states of consciousness. Areas of the brain act in harmony to set our circadian rhythm, get us to sleep and guide us through the cycles of sleep. As we progress through the night, these circuits regulate the passage of sleep from light to deep non-REM sleep, then into REM sleep, four or five times.
The Nocturnal Brain Page 29