Collins need to know? Sleep
The secret to sleeping well and waking refreshed
Doctor Chris Idzikowski

Table of Contents

Cover Page

Title Page

Introduction

1 Knowing the basics

2 Why can’t we sleep?

3 Life’s journey

4 How to sleep better

5 Taking control

6 Sleep disorders

7 Sleep medicine

Glossary

Useful addresses

Index

Copyright

About the Publisher

Introduction

Sleep and wakefulness are two sides of the same coin and just about everyone has had a problem with them at one time or another. For many people the difficulties associated with sleep – sleeplessness, sleepiness, tiredness, fatigue – are short-lived and manageable while for others they become chronic and very hard to cope with.

People who need more than the average amount of sleep, say 9-10 hours a day tend to get little sympathy from those who get by on less. The latter, the ‘short’ sleepers, cannot understand why more is necessary to feel, function and look well. They are likely to know what it is like only when they cannot get enough sleep or their sleep is disrupted, such as from long commutes which do not leave much time for work and sleep, illness, jet lag, shift work, caring for others, etc. They have managed so they will wonder why it is not possible for others to cope – of course, they might lack insight because they are themselves chronically sleep-deprived; rather like someone who has drunk a little alcohol and thinks they are performing as well as before. Hence ‘long’ sleepers have a problem, as do ‘average’ sleepers if their sleep is disrupted and they are not getting enough. Those people with sleep disorders such as insomnia, narcolepsy, sleep apnoea (stopping breathing during sleep) or restless legs will be similarly aware that people who don’t have these disorders seem not to care.

Well, this book does care and its aim is not only to help both the sufferers from sleep disorders but also those who want to feel better rested. After all, it has been shown that daytime napping improves mental performance later in the day. The book takes a systematic approach by first exploring what sleep is, its patterns and different stages. This enables readers to understand what their sleep problem is as well as enabling them to work out solutions for themselves. Chapter 2 runs through all those factors that impact on sleep. Sleep varies over our lifetimes and Chapter 3 examines these changes; it helps to understand whether there is a natural process at work or an underlying problem.

Chapter 4 starts to look at solutions that may not necessarily require medical aid or intervention. Chapter 5 delves even deeper and provides some self-assessment procedures that may give an idea of what is causing the sleep problems.

The field of sleep medicine has grown over the last decade or so. In the US it has become a medical speciality. In the UK, on the other hand, expertise runs across a number of specialities, ranging from general practice to respiratory medicine, ENT surgery, psychiatry, neurology and occupational medicine. Sleep medicine has developed in a way that is shared across countries and Chapters 6 and 7 deal with what are now considered sleep disorders and their specific solutions.

Disturbed or shortened sleep not only has an impact on mental performance, both in terms of concentration and increased risk of car accidents, for instance, but it is also associated with diabetes, obesity, heart disease and strokes. Problems with sleep should be tackled and this book shows how to go about this.

1 Knowing the basics

With our 21st-century lifestyles and the everincreasing need to juggle work and family commitments, getting a good night’s sleep has never seemed more important, yet although we spend a third of our lives asleep, research in this area is still relatively new. What really happens when we are asleep? And why is sleep so important? Although much of this fascinating and complex subject remains a mystery, scientists now have some of the answers to these all-important questions.

Understanding sleep

Sleep is essential for our survival and wellbeing. We all know it makes us feel good, alert and able to cope with our waking lives. But why is it so important? What are the benefits of sleep and what happens when we don’t get enough?

must know

Animal sleep

• Sleep is so essential to animals that Nature has made special arrangements to enable it to happen. Horses’ tendons are specially adapted to allow them to sleep standing up; similar adaptations allow South American sloths to sleep upside down, and migratory birds to sleep on the wing. Dolphin brains are so constructed to enable them to swim continuously while breathing (half their forebrain goes to sleep while the other half remains awake).

• The amount of sleep animals need varies according to their size. Elephants sleep for four hours, for instance; rats for 14.

Why sleep?

Sleep is not an optional extra. Like the food we eat and the air we breathe, it is a fundamental need. Sleep is essential for all living beings. Studies on animals have shown that sleep provides a period of enforced quietness in which they can hide from predators, and that sleep exists in all varieties of mammal, irrespective of their size, temperament and habitat.

The generally held view is that sleep energizes and revives, providing us with an enforced time of rest that allows us to recharge our batteries to cope with the everyday business of living. But many scientists argue that to think of sleep entirely in terms of rest is misleading, because it is also an active period when the restoration and repair of body tissue takes place. It is during sleep, for example, that growth hormones are released in developing babies and children.

There is also evidence to suggest that sleep plays a significant role in brain development, and that learning may improve after sleep. In experiments carried out in the UK and USA, subjects who were allowed to sleep after learning new information were found to have a better recall of the data they had learned than those who had not slept.

To most of us, the benefits of sleep are evident from the way we feel after a good night’s rest. But perhaps a better way to understand the role of sleep is to look at what happens when we don’t sleep.

must know

Rest and sleep

Scientists are baffled about the role of rest in sleep, as the amount of energy saved during sleep is only 100 kcal – the same number of calories as in a large piece of toast.

Effects of sleep deprivation

Classic sleep deprivation experiments consist of depriving subjects of one night’s sleep, then asking them to listen to about 1800 bleeps for an hour or so. About 40 of the bleeps are a second shorter than the others, and these are the ones the subjects have to react to. (Most errors of detection generally occur in the last 15 minutes of the task.) Experiments such as this have proved useful to scientists’ understanding of the consequences of lack of sleep. Findings have shown the main short-term effects to be as follows:

• General lack of wellbeing. Lack of sleep can cause fatigue and grogginess.

• Concentration and vigilance. Experiments have invariably shown damaging effects in these areas. People who have been sleep-deprived are more likely to have difficulty taking in information and to make mistakes at work. In real-life situations requiring constant vigilance, such as driving, the dangers are obvious. Statistics show that 20 per cent of all road accidents are caused by fatigue and that many of these accidents will lead to fatalities.

• Memory. Many people complain that they are more forgetful when they do not get enough sleep. This could be down to a concentration problem but it may also be that sleep deprivation makes it more difficult to retrieve information from the brain’s memory store.

must know

Sleep deprivation

• 20-25 hours of sleep deprivation reduces mental performance to the same level as someone with a blood/alcohol concentration of 0.1 per cent, which is greater than the current maximum for legal driving in the UK – 0.08 per cent.

• The US Department of Transportation estimates that 100,000 accidents every year are caused by people feeling fatigued and/or drowsy, and that it leads to 4 per cent of all traffic-related deaths.

• Mood. Lack of sleep can lead to irritability and over-anxiety, which can have damaging effects on your social life, family and other relationships.

• Immunity. Evidence suggests that lack of sleep may affect the immune system. After vaccination, subjects who may have been sleep-deprived have 50 per cent fewer antibodies than those who have slept adequately. Sleep and the immune system are strongly linked; bacterial cell walls can stimulate the sleep centres directly.

• Rational decision-making. Studies show that sleep deprivation can affect general judgement and decision-making abilities, and that people who are sleep-deprived have difficulty in responding to rapidly changing situations. The real-life consequences can be grave. Fatigue is now known to have been a contributory factor in many international disasters such as the nuclear explosion at Chernobyl, the Exxon Valdez oil spill and the Challenger shuttle explosion.

Apart from these common short-term effects of sleep deprivation, there are also long-term consequences. American research suggests that long-term sleep deprivation (defined as interrupted sleep over a period of about a year) may be linked with obesity. Studies carried out at Colombia University have shown that 73 per cent of people who sleep only 2-4 hours a night are more likely to be obese than those who sleep for seven hours. The reason is unclear but it may be because chemicals that play a key role in appetite and weight gain are released during sleep. Other long-term consequences include extreme anxiety, depression, specific sleep-related disorders and even psychosis.

Key turning points in sleep research

Progress in sleep studies changed significantly when it was found that the brain’s activity could be measured objectively. Here is a summary of the main findings that led to this discovery.

• In the 19th century, British researcher Richard Caton measured the brain’s electrical activity by placing sensors on to the scalp’s surface. He noted that the activity was not constant but increases and decreases over time.

• In the late 1920s, German psychiatrist Hans Berger measured brain activity in the belief that it would help him to calculate psychical energy. Largely discredited, he tragically committed suicide. However, his work on measuring the electrical activity of the brain was pivotal in the development of sleep research.

must know

REM and dreams

The discovery in the late 1950s/early 1960s of the connection between REM sleep (see page 20) and dreaming was one of the most exciting in sleep science because it proved without doubt that the brain was active during sleep. The findings marked the beginning of a new impetus in sleep research which lasted through the 1960s, when psychedelia was much in vogue. By the 1970s, interest had declined.

• In 1939, while working at Chicago University, Nathaniel Kleitman – often called ‘the father of sleep’ – published the first major book on sleep, Sleep and Wakefulness (1939). The generally held view of the scientific and medical establishment was that sleep is a passive condition. Kleitman was one of the few people in the world working on sleep at the time.

• In 1953, PhD student Eugene Aserinsky, while working with Kleitman, noted that the eyes move rapidly during sleep, eventually leading to the name of this state as Rapid Eye Movement (REM) sleep. Around this time, William (Bill) Dement joined them and all three were involved in the discovery that subjects awoken out of REM sleep often report dreaming – a turning point in knowing, as opposed to inferring, what goes on in the mind.

How sleep works

Sleep is a highly complicated but ordered process that is controlled by special wakefulness and sleep centres in the brain that work in tandem with hormones and our own internal body clock. The main players in this fascinating process are described below.

must know

24-hour cycle

Most living organisms, plants and animals, live according to a 24-hour cycle that is dominated by light and darkness. Even death can be part of this cycle, with cardiac arrests and strokes occurring mainly between 6 a.m. and 12 noon – perhaps because this is when blood tends to clot most.

Clocks, cycles and rhythms

We are all governed by a 24-hour cycle called a ‘circadian rhythm’, taken from the Latin words circa, meaning ‘around’, and die, meaning ‘day’. Circadian rhythms underpin everything, from hormone production to when we feel like getting up or going to bed. Our body temperature has a 24-hour rhythm too; minimum body temperature usually occurs around 4 a.m., maximum body temperature around 10-11 p.m. Sleep also roughly follows a 24-hour rhythm.

For most of us, a typical cycle means falling asleep between around 11 p.m. and midnight, and waking up between 6 a.m. and 8 a.m., indicating that we are biologically programmed to be able to fall asleep and wake up at around those times. However, not all clocks keep the correct time, and the biological clock is no exception. It generally runs a little ‘slow’ but is kept to the right time relative to light and darkness by ‘synchronizing’ cues called ‘zeitgebers’. Dawn light is one of the most important and well-understood cues that our body responds to, but the onset of darkness (which stimulates the production of melatonin from the pineal gland) also has a role to play. Other zeitgebers are exercise, mealtimes, social interactions, sounds, and possibly changes in temperature. Sleep itself may be a weak zeitgeber.

Sleep and wakefulness

Working with the ebb and flow of the circadian rhythm are special sleep and wakefulness centres, which are located in a part of the brain called the hypothalamus. The sleep centre is in the same region of the brain that controls temperature (which may be why you sometimes can’t sleep if you are too hot) and the wakefulness centre is near the part that is associated with activity. In an ideal world, the sleep centre will shut down during the day, when the wakefulness centre opens, and open at night, when the wakefulness centre closes. Not surprisingly, good sleepers have strong day-time wakefulness and night-time sleep systems. But if these centres have been damaged (through, say, over-use of caffeine, alcohol or drugs, or due to illness or age), you are likely to have sleeping problems.

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Sleep vs. wakefulness

The discovery of sleep and wakefulness centres in the brain came about as the result of the spread of a brain disease called Encephalitis lethargica between 1917 and 1928. The disease, characterized by a lethargy that turns its sufferers into living statues, became the subject of the Oliver Sachs book Awakenings (1973).

The brain’s sleep centres

must know

Cues

The brain’s metronome or clock runs slowly. Various cues such as light, exercise and food intake keep it synchronized with day and night.

The brain’s metronome

The suprachiasmatic nucleus (SCN), is the brain’s master biological clock, or metronome. It helps to synchronize sleep with the circadian rhythm, as well as regulating many of the bodily functions that affect sleep, such as hormonal secretion and body temperature. Made up of about 20,000 nerve cells, the SCN is located in the brain’s hypothalamus, just behind the eyes, and is immensely important; if it is destroyed, 24-hour rhythms break down. It keeps time with daylight and is believed to work particularly closely with the wakefulness centre of the brain. Scientists also believe it ‘instructs’ the pineal gland to release melatonin, the hormone that signals the onset of darkness.

In 2002, a group of scientists discovered that the SCN is directly connected to a receptor in the retina sensitive to blue light (light from the sky), which enables the brain to identify whether it is light or dark. In blind people, who have damaged retinas, the SCN does not synchronize with daylight and so their ability to sleep is affected.

The role of melatonin

Melatonin is secreted by the pineal gland in the brain (often known as the ‘third eye’ in reptiles because of its sensitivity to light), and is the hormone that ‘tells’ the brain it is dark. Secretion starts when it gets darker, peaks in the middle of the night and stops at dawn. Melatonin is believed to be an important synchronizer of other circadian rhythms and is closely connected with Seasonal Affective Disorder (SAD) and jet lag.

Seasonal Affective Disorder (SAD)

Seasonal affective disorder, or SAD, is a condition in which people suffer depression, insomnia and lethargy in the winter months – hence its alternative name, ‘winter depression’. Normal circadian rhythms dictate that we get up in the light and go to bed in the dark. This is fine in the summer, but, in the case of SAD sufferers, the lack of light in winter is believed to disrupt their body clock so much that getting up on dark winter mornings proves impossible. The problem is believed to be caused by a disruption in their production levels of melatonin, the hormone which acts as the brain’s and body’s signal for darkness. Melatonin is normally produced at night, but in 80 per cent of SAD sufferers, melatonin levels peak just when it’s time to get up. SAD is often treated with light therapy, in which sufferers are subjected to bright light. The light is believed to block the production of melatonin, which kickstarts and resets the body clock.

The role of serotonin

Serotonin as a precursor of melatonin is one of the brain’s chemical messengers and has a major effect on the way the brain works, specifically affecting mood and sleep. (Other chemicals in this group include noradrenaline, dopamine and histamine.) It is produced in the brain from trytophan, an essential amino acid found in certain foods, and levels in the body are negatively affected by poor diet and stress. Lack of serotonin may lead not only to insomnia, but to anxiety and depression, which are in turn two of the greatest disruptors of sleep. Often known as the ‘feel good’ hormone, serotonin is Nature’s own Prozac, and is a crucial in the way many of the more recent antidepressant drugs, known as Selective Serotonin Re-uptake Inhibitors (SSRIs), work.

did you know?

• Serotonin is one of the oldest brain chemicals around. Serotonin neurones existed in animals that appeared on earth 500 million years ago.

• Women produce up to a third less serotonin than men.

What happens when we sleep

Doctors and scientists can now record the activity of the brain in sleep by means of an electro-encephalogram or EEG. Using EEGs in this way has revolutionized our understanding of sleep.

must know

Deep sleep

• Deep sleep usually occurs during the first three hours and takes up to 20-25 per cent of the night.

• Stage 2, or light sleep, occupies around 50 per cent of the night.

• REM sleep occupies around 25 per cent of the night.

The stages of sleep

In an electro-encephalogram (EEG), electrodes are glued to a person’s scalp and then connected to powerful amplifiers that measure brain activity. Their output used to be printed on paper, but can now be seen on a computer monitor in the form of a graph called a hypnogram, or polysomnograph, which shows the brainwaves emitted during sleep. Eye activity and muscle tone are also recorded.

Using the EEG in this way has shown that people have two different kinds of sleep: non-REM (Rapid Eye Movement) sleep and REM, or dreaming, sleep, and that they go through five different stages within these two main types: Stage 1 (drowsiness), Stage 2 (light sleep), Stages 3 and 4 (deep sleep, sometimes called delta or slow-wave sleep) and Stage 5 (also known as REM sleep).

Stage 1: drowsiness

This is a short transitional stage, lasting only about 10-15 minutes. Your brainwaves will start to slow down from the normal ‘alpha rhythm’ measurement of 8-12 cycles per second, your muscles will start to relax and your eyes begin to roll. Polysomnographs taken at this stage show a 50 per cent reduction in activity compared to when awake. Although your eyes will be closed, if you are aroused from sleep at this stage you may feel as if you have not slept at all.

Hypnogram

Set of traces

Stage 2: light sleep

As you descend further into sleep, the relaxed alpha rhythm is replaced by a faster wave form of 12-14 cycles per second called a ‘sleep spindle’ (because of the spindle shape it makes on the computer screen). At this point the systems that maintain wakefulness are letting go and the sleep-promoting systems are switching on. This stage usually lasts 30-40 minutes.

Stages 3 and 4: deep sleep, delta or slow-wave sleep

Slow-wave sleep lasts for roughly the first three hours of the night and it is very difficult to wake people up from it. People who are woken at this stage often act quite strangely, almost as if they are drunk.

must know

Ultradian rhythm

Scientists believe there may be a brain rhythm that is mainly revealed during sleep as a 90-minute REM cycle. As this lasts less than 24 hours it is known as an ‘ultradian rhythm’ (Ultra from the Latin for ‘beyond’). Dreams occur on a roughly 90-minute cycle.

At the deep-sleep stage, the EEG shows highamplitude slow waves. The mind begins to drift, thoughts are unfocused, and the brain becomes ‘dormant’. A person in this stage of sleep tends to stop moving and their postural muscles relax. Heart rate and breathing slows, the body temperature ‘thermostat’ in the hypothalamus is lowered and body temperature reduced. Kidney function decreases and less urine is produced.

Stage 5: Rapid Eye Movement (REM) sleep

Stage 5 sleep is commonly known as Rapid Eye Movement, or REM sleep, named after the darting eye movements that have been observed in people in this sleep stage. It appears after 80-90 minutes’ sleep in recurring phases known as an REM cycle. It initially lasts for about ten minutes, then increases in length, with the final one lasting for about an hour. In young adults, REM sleep can last for up to two hours in total.

For many sleep scientists, REM sleep is the most interesting and exciting of all sleep stages, for this is when dreaming occurs, and is when the brain is most active. In fact, curiously, EEGs taken at this time are more similar to those taken during wakefulness than at other sleep stages. The brain shows increased cerebral metabolism, cerebral blood flow, intracranial pressure and brain temperature, and many parts of the brain that control functions such as heart rate, blood pressure, breathing, body and brain temperature and sweating are less well regulated than at other times. Even sexual organs are aroused and men often have penile erections. In fact, there was a time when REM EEGs were used to determine whether men’s impotence was physical or psychological, though this has all changed in recent years with the introduction of Viagra.

must know

Are you a dreamer?

If you don’t think you dream, try setting your alarm clock at 15-20 minutes earlier than your usual morning wake-up time. This will almost certainly ensure that you will be awoken out of REM sleep. Go to bed preparing yourself to remember what is in your mind when you wake up. When the alarm goes off, think about what has been going through your mind.

REM sleep and dreaming

Scientists believe we dream during REM sleep, and that the dreams become more vivid as the sleep stage progresses. Most REM sleep occurs towards the end of the night and can sometimes reach its peak in the early morning, (which is why you can often remember dreams clearly just as you wake up). But the memory of the dream usually fades within minutes.

Sigmund Freud and dreams

Although he originally trained as a doctor, Sigmund Freud (1856-1939) is best known for his study of the mind, and is often referred to as the father of psychoanalysis. Freud believed that the mind consisted of three main elements: the ego (the conscious self), the superego (the mind’s moral guardian) and the id (psychic and unconscious mental energy), and that the demands of the id, left unchecked during sleep, were expressed in dreams.

In Freud’s psychodynamic theory, dreams symbolized unconscious thoughts and mental processes, and interpreting their meaning was a ‘royal road’ to understanding the subconscious mind. One of Freud’s contemporaries, Carl Jung (1865-1961), formulated the idea of the ‘collective unconscious’ (a reservoir of memories and experiences), his list of the many recurring themes in dreams including: water, being trapped, travelling, running, being chased, death, choking, falling, houses, flying, nudity, being late and sex.

Freud’s influence on psychiatric thought has now largely declined, but his book The Interpretation of Dreams (1900) remains one of the most significant works of the 20th century.

REM sleep has often been described as paradoxical because it has many contradictions. Although EEG readings show that the brain is so active at this time that it may be using even more energy than during wakefulness, the muscles, by contrast, are completely paralyzed, apart from rapid eye movements and the odd, involuntary twitching of fingers. Since vivid dreams also occur at this time, some people believe the muscle paralysis is there to stop the dreams from being physically acted out.

did you know?

During REM sleep your brain is as active as when you are awake.

Dreaming through the ages

Dreaming has intrigued and fascinated people for thousands of years before the works of Sigmund Freud, and many of the world’s greatest civilizations and religions have used dreams to guide their everyday lives. Let us look at some of the most famous examples below.

did you know?

An ancient Hindu tale that is still relevant today describes three states of mind: the state of wakefulness (vaiswanara), when a person perceives ‘what is presented to them by their senses’, the state of dreaming sleep (taijasa) ‘which can reflect in the mind what has happened in a person’s past’, and the state of dreamless sleep (prajna) when ‘the veil of unconsciousness envelops thought and knowledge, and the subtle impressions of the mind apparently vanish’.

The ancient Egyptians

By around 2000 bc, the ancient Egyptians were already transcribing their dreams on to papyrus. Egyptians believed that dreams brought messages from the gods and that dreaming was the best way of attaining divine revelation. They developed methods for inducing or incubating dreams, including building sanctuaries that had special beds for dreaming.

The ancient Greeks

Sanctuaries and shrines for promoting dreams were also adopted by the Greeks, who in addition had specific dream rituals. Those entering the Shrine of Apollo at Delphi were required to abstain from sex, or eating meat, fish and fowl two days before. Once in the shrine, they made an animal sacrifice to the god from whom they wanted to receive the dream and would then sleep on the skin of the sacrificed animal, sometimes near the statue of the appropriate deity. The Greek god Hypnos was thought to bring sleep to mortals and his son Morpheus was said to send warnings and prophecies to those sleeping in the temples.

The early Christians

The Judeo-Christian tradition also used dreams as a guide to waking behaviour, most notably in the story of Jacob’s dream of the ladder going up to heaven recounted in Genesis, which was seen as a turning point in his spiritual development. Various books from the Old Testament used dreams for guidance – it was assumed that the conventional way for God to communicate with his people was through dreams. Dreams were similarly used in the New Testament; for example, in stories of the Flight into Egypt and the dream of the Magi at the birth of Christ.

want to know more?

Take it to the next level…

• Chronotherapy 180

• Circadian rhythm disorders 139

• Light 38

• Light therapy 178

• Melatonin supplements 178

• Seasonal Affective Disorder (SAD) 17

• The work of sleep clinics 168

Other sources

• For professional sleep research societies, visit www.wfsrs.org

• To read specialist journals on sleep, visit www.journalsleep.org

• For brain basics and disorders, go to www.ninds.nih.gov or www.websciences.org/s ltbr/

• For contemporary discussion and links on sleep, visit www.neuronic.com or read sleep blogs: scienceblogs.com/clock/

In the first century ad, Ignatius of Antioch dreamt of angels singing alternating chants and introduced this antiphonal singing in monastic communities as a consequence. (Ignatius could possibly be described as one of the early sleep researchers as he claimed that all people dreamt and that this could be observed by their movements when asleep!) And in the fourth century, Chrysostom declared that dreams were symbolic reflections of a spiritual world.

The early philosophers

The early philosophers had opposing views on dreams. Plato argued that there was a world beyond the physical one and that it was possible to communicate with it through dreams, while Aristotle argued that knowledge was gained through sense and reason and that there were no divine communication pathways of communication – dreams were just the remnants of an overly stimulating wakefulness. The debate still continues…

2 Why can’t we sleep?

Surveys show that 95 per cent of us will suffer from sleeping problems at some point in our lives, and insomnia is cited as one of the main reasons for visits to the doctor. But what is insomnia? And, more importantly, why do we get it? All too often the answer lies within. This chapter looks at the important roles that Nature, lifestyle and environment have to play.

All about insomnia

Studies show that 50 per cent of us have symptoms of insomnia at any given time. We often use the word ‘insomnia’ when we miss one night’s sleep. But what does insomnia really mean?

What is insomnia?

In normal usage ‘insomnia’ just means not being able to sleep. The inability to sleep can be caused by literally anything. Sometimes people talk about insomnia when they have not given themselves enough time to sleep, but when considered by a sleep disorder specialist, insomnia is often just regarded as a symptom and a cause is sought, e.g. depression (see page 156). Nowadays a sleep disorder specialist may regard insomnia as a disorder in its own right with very specific sleep-related causes (see pages 127-31). The changes in the usage of the word can cause confusion (particularly when surveys are conducted). An outdated classification simply described three types:

did you know?

• Insomnia is the most common mental health problem in the UK.

• One in ten people will suffer from chronic insomnia at some point in their lives.

• Transient insomnia – short-term sleeping problems (usually lasting only a few days). Often caused by one-off changes in your sleep cycle, such as long-distance travel and jet lag, or illness. This is by far the most common type, and accounts for about 75 per cent of all cases of insomnia.

• Short-term insomnia – sleeping problems caused by a more prolonged period of stress, due to, say, financial problems or marital break-up. This can last for weeks.

• Chronic insomnia – the often inevitable result of untreated short-term insomnia. It can last for months, and, in rare cases, years. It is a long-term problem that often recurs.

Sleeplessness and insomnia

It may be better to use two words: ‘sleeplessness’ for the times that sleep is impossible, but you know why; and ‘insomnia’ for the times that you do not know why you cannot sleep. Some reasons for sleeplessness include:

• lifestyle (work, shifts, caring for an invalid, children)

• poor sleeping environment (noise, uncomfortable mattress, etc.)

• stress (bereavement, divorce, etc.)

• a poor diet

• stimulants, medicines and drugs

must know

Using sleeping pills

Prescription of sleeping pills costs the UK about £22.4 million per year. About 15.5 million prescriptions are written. Taking sleeping pills has been shown to increase the risk of road accidents (last year there were 32,220 serious injuries and deaths on UK roads).

As a general rule, a good way to find out if you have true insomnia is to ask yourself if there is any obvious reason for your sleeping problems. If not, and you have had the problem for a few weeks, then you are likely to be suffering from the condition.

Diagnosing insomnia

Insomnia can develop from sleeplessness, and often patients will know when their sleep problems started but cannot understand why they have not gone away. Psychiatrists rarely diagnose insomnia but when they do the following conditions must be met:

• The time it takes to get to sleep must be more than 30 minutes. Total sleep time during the night is usually between three to six hours. The sleep may be unrefreshing.

• The problem must occur three or more nights a week.

• The insomnia causes major problems in daytime functioning (socially, at home, at work).

• It must have lasted for three months or longer.

• There are no environmental, lifestyle, medical or psychiatric causes for the problem.

The role of Nature

Understanding when our bodies are working against us can sometimes be half the battle when trying to understand why we can’t sleep. Here are some of the natural factors that can affect sleep.

must know

Women and sleeping

Polls carried out in the USA by the National Sleep Foundation found the following:

• Almost three out of four women get less than eight hours’ sleep a night.

• Sleep is disturbed for 2.5 days on average during the menstrual cycle.

• More women complain of sleep problems during menstruation (71 per cent) than during the week preceding menstruation (43 per cent).

• Sleep-disrupting conditions such as anxiety and depression are twice as likely to occur in women than in men.

Gender

It is a sad fact of life that you are more likely to have sleep problems if you are a woman. The reason for this is partly due to the female bodily cycles. Much of women’s lives is governed by the sex hormones oestrogen and progesterone, and hormonal fluctuations, as in the menstrual cycle, pregnancy and the menopause, can severely affect sleep either directly, or through their effects on anxiety and general mood. Pre-menstrual women commonly report sleeping difficulties in the week before their period starts, but even women who don’t suffer from pre-menstrual symptoms can still take longer to fall asleep, wake more often and feel less refreshed after sleep during the second phase of their cycles. Sleep disturbances also become more common during the menopause, when women report waking up more often at night and feeling more tired during the day.

Studies on the effects on sleep of Hormone Replacement Therapy (HRT) and oral contraceptives have shown that these hormones have direct effects on the brain. Oestrogen has widespread effects on mental performance, mood, movement coordination and pain. However, the monthly fluctuation of oestrogen and progesterone impacts on cognitive function, mood, appetite and temperature, as well as the sexual organs and breasts, making it more difficult to work out how they affect sleep directly.

There is evidence to suggest that women’s role in society may affect their sleep even more than hormonal changes. The added pressures many women face of juggling stressful jobs with their roles as mothers and wives can often pose an intolerable burden, exacerbated by the fact that many women ignore their fatigue.

Age

Ageing can greatly affect sleep, with the number of hours declining as you get older. While a young adult will sleep on average for 7-8 hours, by old age this will go down to about six. Quality of sleep is affected too. Stage 4 sleep is reduced, and the proportion of REM sleep, which makes up abut 50 per cent of baby sleep, will, in the latter stages of life, go down to 15-20 per cent. Although the cause may be inevitable, there are still steps you can take to improve the situation (see Chapter 4).

General constitution

Your sleep is more likely to be poor if your general health is poor, even if you are not suffering from a specifically sleep-related disorder (see Chapter 6). Conditions such as heart disease, general breathing problems and arthritis can make it difficult to get comfortable at night, and will almost certainly have an impact on your sleep. Consult your doctor if this becomes an issue. For many people emotional issues and character make-up may come into play.

must know

Adult sleep A recent US National Sleep Foundation survey looking at the relationship of sleep problems in adults aged between 55-84 found:

• Nearly one in four adults had at least four medical conditions.

• Depression, heart disease, pain and memory problems were most associated with insomnia.

• Ninety per cent of those that did not have any medical condition thought their sleep quality was good or excellent. This went down to 78 per cent if they had 1-3 medical conditions, and 59 per cent if they had four or more conditions.

• Obesity, arthritis, diabetes, lung disease, stroke and osteoporosis were more likely to be associated with other sleep problems (e.g. snoring, restless legs).

The role of diet

The role of food and drink in sleep is often overlooked but there is increasing evidence that healthy eating habits can have many beneficial effects. The first stage is to identify and eliminate the main sleep spoilers.

must know

UK safe limits for alcohol

• Men should drink no more than 21 units of alcohol per week (and no more than four units in any one day).

• Women should drink no more than 14 units of alcohol per week (and no more than three units in any one day).

• Pregnant women: if you have one or two drinks of alcohol (one or two units), once or twice a week, it is unlikely to harm your unborn baby. However, the exact safe limit is not known.

Alcohol

Drinking small amounts of alcohol (especially a glass of wine with meals) can be pleasurable, and its benefits well recognized. The problem comes when alcohol is drunk in large doses.

Drinking alcohol at night is commonly believed to be helpful for sleep. This is a myth. Drinking large doses may make you fall into a deep sleep straight away, but as soon as the immediate effects of the alcohol wear off (usually after 3-5 hours), you will wake up feeling exhausted, and your sleep is likely to be disrupted for the rest of the night. Drinking large amounts of alcohol can depress brain activity and induce unconsciousness. Breathing is also invariably impaired, leading to snoring. Alcohol also has a diuretic affect, which means that, depending on how much you’ve drunk, you could end up getting up to go the toilet several times during the night.

Caffeine

Caffeine is a very powerful stimulant that is known to cause the delay of sleep onset. Studies have shown that a dose equivalent to one cup of coffee taken at bedtime can both increase the time taken to fall asleep and decrease sleep quality, especially in non-REM deep sleep (see page 19). In a few individuals, a dose of coffee in the morning can also have an effect the following night, indicating that extremely low concentrations of caffeine can affect sleep. Like all stimulants, caffeine may make you feel increasingly alert during the day, but, as well as causing insomnia, prolonged, high-dose usage (more than six cups of coffee a day) can lead to the following nasty side-effects:

How much alcohol is in your drink?

Sample drink | Quantity | Alcohol by volume | Units
Can of lager | 500ml | 4.00% | 2
Glass of cider | 500ml | 4.00% | 2
Alcopop | 400ml | 5.00% | 2
X-Strong lager | 500ml | 8.00% | 4
Glass of wine | 160ml | 12.50% | 2
Cocktail | 125ml | 40.00% | 5
Shot of spirits | 25ml | 40.00% | 1

Note: A unit is 10ml of alcohol, whether it is spirits, lager or wine.

• persistent anxiety

• an inability to concentrate

• increased muscle tension

• diuresis (increased urination)

• agitation, excitement and panic attacks (with high doses)

• vertigo, dizziness, tinnitus, convulsions

• increased body temperature

• confusion, disorientation, paranoia

• palpitations

• nausea

watch out!

A good night’s sleep does not result from high doses of alcohol. A night’s sleep deprivation will enhance the effects of alcohol and after five nights of partial sleep loss, three drinks will have the same effect on your body as six would on a regular night.

must know

Caffeine

• Caffeine is readily absorbed and peak concentrations occur 30-60 minutes in young adults after ingesting it. High doses slow the metabolism down and can remain in the brain for 9-15 hours.

• Percolated coffee usually contains more caffeine than instant. If the coffee grounds are boiled during preparation, as is common in Scandinavian countries, the caffeine content can be as high as 500mg per cup.

• Tea brewed directly from crushed leaves has more caffeine than tea produced with a tea bag.

• Plain chocolate contains more caffeine than milk chocolate.

Caffeine enters the bloodstream very quickly and can take between three and seven hours to leave the body. Its effects on people can be variable – some people regularly drink caffeine-laden drinks at night-time with no ill-effects; others cannot even drink one cup in the morning without it affecting them at night. Scientists believe this may be because caffeine-sensitive individuals metabolize the substance more slowly (see opposite, for factors involved in metabolizing caffeine).

Research shows that if you are not a habitual coffee drinker, the effects will be greater; and that caffeine metabolism varies with age (children, for example, tend to metabolize it more quickly).

Although caffeine is normally associated with coffee, it is found in medicines and many other foods and drinks, namely:

• tea

• chocolate, cocoa and all other chocolate-flavoured products

• over-the-counter stimulants (e.g. Pro-plus)

• painkillers (e.g. Anadin)

• herbal preparations (e.g. Guarin)

• some cola drinks

• Lucozade

• ‘energy’ drinks (e.g. Red Bull)

To find out how much caffeine you are really consuming, see the main caffeine offenders, opposite.

The absorption and metabolism of caffeine

Varied or little effect

Heredity Caffeine metabolism is controlled by many genes and racial differences exist

Gender Exercise and stress have no reliable effect on the absorption or metabolism of caffeine

Pregnancy There are no placental barriers to caffeine so the foetus is continuously exposed

Slowers-down

Oral contraceptives, late pregnancy and liver disease cause caffeine to be eliminated more slowly

It has been thought that grapefruit juice, though not other citrus juices, slows down metabolism. The data for this has now proved controversial

Some drugs like cimetidine, disulfiram, even alcohol, may slow down caffeine metabolism

Speeders-up

Smoking induces liver enzymes which break caffeine down

Rifamprin

The main caffeine offenders

Foodstuff | Plant | Plant caffeine content w/w | Caffeine dose/‘cup’
Tea | Dried leaves | 1-5% | 10-100mg (average 40mg)
Coffee | Beans | 0.75-2.0% | 30-150mg
‘Decaffeinated’ coffee | Beans | 0.75-2.0% | 5mg
Cocoa | Seeds | 0.013-1.7% | 2-50mg (average 5mg)
Chocolate | Seeds |  | 2-63mg/50g
Cola drinks | Nuts | 1.5-2.0% | 25-100mg (synthetic)

did you know?

Coffee is an ancient commodity. In AD 575, about 500 years before it became a hot beverage, the crushed beans were mixed with fat and used by Ethiopian mountain warriors to provide an energy boost during long treks and warfare.

must know

Sugar

Sugar does not give you energy. A study carried out at Loughborough University, UK evaluated the energy-giving effects of sugar on ten healthy young adults. Their sleep was restricted to five hours the night before so that they would be sleepy in the afternoon, and half were given a ‘high-energy’ drink containing high levels of sugar but low levels of caffeine, and the other half a drink containing low levels of both. When submitted to vigilence and sleepiness tests the high-sugar drinkers made twice as many errors and showed higher levels of sleepiness than the control group, as well as delayed reaction times.

Sugar

Sugar can have a negative impact on sleep patterns because of its effect on insulin and blood sugar levels. It is released into the bloodstream to give you that instant ‘high’, but then departs from your system just as quickly, leaving you exhausted. In fact, you feel so tired that your instant impulse is to have yet another sugar fix to make you feel better. And so the cycle goes on. The continuing effect of these highs and lows can leave you feeling drained, or – depending on when you last had your sugar dose – over-excited, with pounding palpitations that stop you from sleeping. The disruptive impact on blood sugar levels can also cause sleep-disrupting hormonal imbalances in women. Sugar is found not only in biscuits and sweets, but also in fizzy drinks, refined wheat, tomato ketchup, baked beans and many processed foods. Read all food labels carefully.

‘Good sleep’ foods

There is some evidence to suggest that eating slowrelease energy foods, or low glycaemic index foods, (foods that keep blood sugar levels stable), may improve general health and sleep quality (as well as helping the individual to lose fat). The idea is that the lower the glycaemic rating of a particular food, the more slowly energy, in the form of glucose, will be released into the body (see Low glycaemic index foods, opposite). Thus glucose and insulin levels are prevented from plummeting during the night, which may be beneficial for sleep. Foods such as turkey and dairy products may also be helpful, as they are high in tryptophan – the amino acid that the body uses to produce the sleep-inducing hormones serotonin and melatonin (see pages 16-17).

Low glycaemic index foods

Food | Carb (g) | Fibre (g) | Cal (kcal)
Granary bread, 1 slice | 14 | 1.9 | 71
Rye bread, 1 slice | 13.7 | 1.7 | 66
Chickpeas, small can, 200g | 32.2 | - | 230
High-fibre bran, 40g | 18.4 | 10.8 | 112
Rolled oats, 100g | 62 | 7 | 368
Porridge (cooked and made with water) 100g | 8.1 | 0.8 | 46
Apple, 1 medium | 21 | 3.8 | 82
Avocado, half medium | 8 | 3.4 | 160
Ham, honey-roast, 50g | 1.4 | 0.5 | 68
Pumpkin seeds, 25g | 11.8 | 1.1 | 143
Spaghetti, cooked weight 100g | 22.2 | - | 113

What to eat when

When we eat can be as important as what we eat. This is a question of balance. Hunger can keep you awake, so having a light snack before you go to bed can be advisable. On the other hand, going to bed with a stomach that is over-full may cause indigestion and feelings of discomfort that will keep you awake all night, especially if you have eaten fatty and rich foods that make your digestive system work harder.

must know

Diet

Studies on the effect of milky or malted drinks on sleep appeared to show benefits. However, evidence does suggest that non-milky herbal teas are just as effective in promoting a good night’s sleep.

As a rule it is best to eat your main meal at lunch time or early evening, and to eat small amounts of light food at night-time. Snacking if you wake during the night is not a good idea. Your body may come to expect food at this time, and you will carry on waking up in the night to satisfy your hunger.

Lifestyle

The way we live can provide a crucial pointer to our sleep problems. Stress, shift work, smoking and jet lag can all be contributing factors. It can be hard to change the habits of a lifetime, but when it comes to sleep, small changes can go a long way.

must know

Sleep in ex-smokers

Sleep disturbances and related daytime symptoms may leave the ex-smoker less able to cope with everyday stress, therefore increasing the likelihood of relapse. Studies have found that ex-smokers complaining of broken sleep are the most vulnerable.

Stress

This is by far the most common cause of insomnia, and can be short-term (caused, say, by the arrival of a new baby) or prolonged (juggling a career and family, or caring for someone who is ill).

Stress has been with us since ancient times, when our forebears used the natural ‘fight or flight’ response to deal with threatening situations such as attack. The causes of stress may be different now but the basic response is still there. ‘Fight or flight’ increases breathing rate, heart beat, and the production of the stress hormones cortisol and adrenaline; mental awareness is heightened and blood rushes to the muscles; the body is on red alert to deal with whatever crisis it is faced with. Doctors acknowledge that we all need some degree of fight or flight in our lives because it satisfies a primitive urge for survival. But prolonged stress can have damaging effects on both health and sleep. It is well documented that long-term stress can lead to anxiety and depression – two major sleep disruptors that can be the cause of many sleep-related disorders (see Chapter 6). Acknowledging when things have got out of hand and taking stress-relieving measures is the only solution (see Chapter 5).

Smoking

Despite the well-known risks of smoking, this still remains a major problem – mostly due to the highly addictive nature of nicotine itself, which can make it extremely difficult for habitual smokers to stop. Withdrawal symptoms can begin quickly – often within a few hours of the last cigarette – leading to sleep disturbances. The brain’s nicotine receptors respond very rapidly to the lack of nicotine, which is why for habitual smokers the first cigarette of the day can bring the most relief, even though smoking in the night can cause disrupted sleep.

must know

NRT

Nicotine replacement therapy (NRT), which reduces the urge to smoke, is recognized as an effective aid to stop smoking, and increases cessation rates. Unfortunately, nicotine patches can sometimes be over-stimulating, leading to insomnia. The 24-hour patches are less problematic than the 16-hour ones, however.

The combined impact of the brain’s response to the lack of nicotine and the breathing problems that all smokers invariably suffer from mean that nicotine is most definitely not good for sleep.

Sadly, smoking is a vicious cycle that creates numerous problems. Many people start the habit because they find it useful for maintaining or increasing their alertness. (When inhaled, nicotine quickly stimulates the heart, brain and adrenal glands.) This is particularly true among young people and sufferers of sleep-related disorders. The need to boost alertness with nicotine reinforces the use of tobacco. Tobacco disturbs sleep, reducing daytime alertness, which in turn reinforces the use of tobacco. Apart from keeping you awake, there is evidence to suggest that nicotine may affect sleep in other, more indirect ways too. Smoking is believed to affect blood sugar levels, which can make you irritable, and smokers are also statistically more likely to be coffee-drinkers, the combined effect of nicotine and caffeine having a disastrous long-term impact on sleep duration and quality.

Environment

Studies have shown that the sleeping environment can have a great impact on sleeping patterns. The degree of noise, vibration, light, humidity, or sharing a room with a partner who snores – all can have a significant part to play.

must know

Light and the retina

The retina consists of receptors that are sensitive to light. One group known as the ganglion cells are particularly sensitive to light, and in particular to blue light (such as that of the sky). These cells make a direct connection to the biological clock (see page 14) which controls the time that we are likely to sleep. About 20 per cent of light gets through the eyelids when the eyes are shut, which means that we can be affected by light and the time that we sleep even when we are in bed with our eyes shut!

Light

Light can have a profound effect upon our wellbeing, both consciously and unconsciously. The conscious effects of light have been known for many years. Numerous studies have shown that subjects exposed to bright light experience significant improvements in mood and a decrease in feelings of tiredness. Indeed, conditions such as Seasonal Affective Disorder (SAD – see page 17) are even treated by exposure to bright light. In recent years, scientists have learned that it is blue light (or natural skylight) that has the greatest effect on our sleeping patterns, because of the unique and very special influence it has on our internal bodyclock – the mechanism that determines what time we go to sleep at night and get up in the morning. (See The brain’s metronome, see page 16).

Any disruption to the bodyclock can lead us believe that it is daytime rather than night, and to react accordingly. Blue light, it is believed, also inhibits the night-time secretion of melatonin, the hormone that signals the onset of darkness (see page 16), thus preventing or disrupting sleep. (When it is dark, melatonin secretion rises and peaks at the darkest time and then goes down until dawn, when the biological clock is reset to wake.) The effects of blue light are unconscious.

There are also conscious effects of perceived light: the brighter the light in your bedroom, the more alert and less sleepy you will feel. Taking lux as a measurement of light intensity (see the table below), normal indoor lighting measures around 200 ‘lux’, while a cloudy day is around 10,000 ‘lux’ – significantly lighter, which makes it crucial to block it out as much as possible when you go to sleep. If you cannot control the amount of light you are exposed to and don’t want to hide your eyes with a pillow, consider using an eye mask.

did you know?

Blind or visually impaired people have no internal bodyclocks because their retinas are so damaged that light cannot enter the brain. They will therefore have no natural sense of when to get up and when to go to bed.

In recent years, street and industrial lighting has increased dramatically, which has had a great impact on normal daylight hours and in some people can have the effect of disturbing the timing of their internal clocks. Again, an eye mask, thick curtains, or curtains with extra lining may help.

The relative intensity of different forms of light

Illuminance | Example
0.00005 lux | Starlight
1 lux | Moonlight
400 lux | A brightly lit office
400 lux | Sunrise or sunset on a clear day.
1000 lux | Typical TV studio lighting
32,000 lux | Sunlight on an average day (min.)
100,000 lux | Sunlight on an average day (max.)

Note: Lux is a measure of the intensity of light.

must know

Decibels

Noise is measured in decibels (dB). A 3dB change is detectable but because of the scale used with decibels an increase of 3 means that the noise level has actually doubled.

There is some evidence to suggest that using coloured lighting may affect the ‘colour temperature’ of a room. Colours can be pleasing to some people and irritating for others so it is important not to be too assertive as to which are best. However, in general the warmer colours of sunset tend to be associated with deep sleep while the cooler colours of dawn are associated with darkness.

Humidity

One of the most common breathing-related sleeping disorders is asthma, which is often caused by allergens found in the faeces of house dust mites. The relative humidity of your surroundings will be the key factor that influences the prevalence of these mites, which can live in conditions where there is no liquid to drink as they can extract sufficient water from the environment if the humidity is high enough. Surveys in temperate climates show that mite prevalence varies according to seasonal fluctuations in indoor humidity. Mites are absent or rare in homes in dry climates unless use of evaporative coolers adds the moisture to the air that is necessary for their survival. Maintaining average daily indoor humidity below 50 per cent will prevent mite population growth and subsequent sleep-disrupting allergens. Even if humidity is lowered, it can take several months for all the allergens to disappear, however.

Noise

People can be awoken by neutral sounds louder than 45 decibels (dB), the equivalent to someone talking quietly (a lawnmower is around 105dB and the threshold for injury to the ear is around 140dB). However, sounds as low as 20dB (below the hearing threshold) can prevent you from falling asleep.

Conversely, continuous background sounds can be soporific and it seems that sounds even below 20dB can induce sleepiness – a clear danger for lorry and train drivers. Irregular high-frequency noise can have the opposite effect and be intrusive.

Noise table

Type of noise | Decibels (dB)
Faintest, audible sounds | 0.2-20
TV sound studio, quiet library | 20-30
Quiet office | 40-50
Conversation | 50-60
Primary school classroom, loud radio | 60-70
Power drill | 85-90
Road drill | 100-110
Chainsaw | 110-115
Jet aircraft taking off, 25 miles away | 140

must know

Vibrations

Vibration can affect sleep just as much as noise. It has been found that even quiet traffic noise of 50dB, when accompanied by vibrations, is more disturbing than when there is just noise. REM sleep is more affected than other stages of sleep. Performance the following day can be impaired.

Noise is a problem in many hospitals, particularly in intensive care units. Research has shown that noise in the latter does disturb sleep, and it could be argued that healing processes could be facilitated if natural sleep were promoted. Studies have shown that in neonatal intensive care units, for example, very low birth weight babies sleep more deeply and cry less if quiet hours are introduced. Playing ocean sounds to mask the noise in an intensive care unit has been found to work.

In controlled studies, traffic noise has been shown to increase the time it takes to get to sleep and to lead to greater irritability. Aircraft noise from airports can affect EEG results, showing lighter sleep. However, despite the fact that higher psychiatric hospital admission rates, GP visits and self-reported health problems have been reported near airports, the effects are highly variable from individual to individual, some being oblivious to the noise levels, others not.

Installing double- or triple-glazing in your home may help, as will wearing ear-plugs, though there is an obvious danger with the latter of possibly life-saving alarms not being heard.

Snoring partners

Many people find snoring amusing, but its long-term effects can be damaging to both the person who snores and their partner. Snoring (covered in more detail on pages 134-6) has been reported to disturb at least 20 per cent of the adult population and has led to numerous social problems ranging from marital disharmony to murder.

watch out!

The disadvantage of not seeking help for your snoring problem is that you may be suffering from a more serious sleep breathing disorder: Obstructive Sleep Apnoea (OSA – see page 132).

A survey using a throat microphone found that 81 per cent of men snored for more than 10 per cent of the night and 22 per cent snored for more than 50 per cent of the night. Other studies have found that women exposed to loud snoring have a higher rate of health complaints, including (not surprisingly) hearing loss!

Although snoring is less prevalent among women, research shows that between 10 and 20 per cent suffer habitual problems and that the incidence increases after the menopause (see page 55).

Snoring is associated with being male. This may be because the anatomy of men and women is different, while the distribution of body fat also predisposes men to snoring. It has also been suggested that women perceive and report snoring more than men. Although there is no universal cure for snoring (possibly because it has so many different anatomical causes), limiting alcohol intake and losing weight may help – research shows there is a clear link between obesity and snoring.

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