Why do humans and other mammals sleep ? The topic of sleep has been a
focus of widespread research, and yet this fascinating question continues
to prove surprisingly difficult to answer. Does sleep have a specific
role in stimulating body tissues to repair themselves, for example, or
is physical rest all that is required for restitution? Does sleep have
different functions in different mammals? Why We Sleep is an authoritative
and readable account of the continuing controversies, written from a broad
biological perspective. The author, a leading figure in sleep research,
critically examines traditional views, and puts forward many conclusions
and hypotheses of his own, suggesting, for example, that the usual practice
of dividing sleep into REM and non-REM may obscure other divisions of
greater functional significance. The book should appeal not only to sleep
researchers and students of psychology, zoology, and physiology, but to
many general readers with a scientific or medical background.
Dr James Horne is Reader at the Department of Human Sciences, Loughborough
- 1.1 Early sleep theories
- 1.2 Daily sleep and wakefulness
- 1.3 Measuring sleep
2. Sleep deprivation
- 2.1 Problems with animal experiments
- 2.2 Recent animal experiments
- 2.3 Some problems with human experiments
- 2.4 1896-the first real sleep deprivation experiment on humans
- 2.5 The longest study-264 hours without sleep
- 2.6 Abnormal behaviour
- 2.7 The longest study with more than one subject-205 hours
- 2.8 The Walter Reed experiments
- 2.9 Motivation and cerebral "impairment"
- 2.10 Tasks sensitive to sleep deprivation
- 2.11 Higher levels of cerebral function
- 2.12 Spare cerebral-capacity
- 2.13 Performance measures are too limited
- 2.14 Two types of sleepiness?
- 2.15 Short-term sleep restriction
- 2.16 Age and sleep deprivation
- 2.17 Does repeated deprivation produce any immunity to sleep loss?
- 2.18 Can sleep deprivation effects be sped up or slowed down?
- 2.19 Do long and short sleepers differ in their recovery sleep?
- 2.20 Epilepsy
- 2.21 Other effects on the human EEG
3. Physiological effects of sleep deprivation
- 3.1 The first major physiological study-Kleitman (1923)
- 3.2 The next 50 years
- 3.3 Body 'restitution' and sleep
- 3.4 Effects on exercise
- 3.5 The control of body temperature (thermoregulation)
- 3.6 Other aspects of homeostasis
- 3.7 Update on hormone changes
- 3.8 The immune system
- 3.9 Conclusions about sleep deprivation in humans
4. Body restitution and sleep
- 4.1 Tissue restitution: protein turnover and cell division
- 4.2 Factors influencing protein turnover and the cell cycle
- 4.3 Feeding and protein turnover
- 4.4 Mitosis, sleep and physical activity
- 4.5 Metabolism during sleep and the energy cost of restitution
- 4.6 "Cell energy charge" and sleep
- 4.7 Human growth hormone release during sleep
- 4.8 Other hormonal changes during human sleep
- 4.9 Thyroid activity and sleep-body versus brain restitution
- 4.10 The effects of exercise on sleep-background
- 4.11 Is body heating the key?
- 4.12 Conclusions-does sleep promote enhanced body restitution?
5. Waking awareness, subsequent sleep, and cerebral "restitution"
- 5.1 Background
- 5.2 Influences of wakefulness on subsequent sleep
- 5.3 SWS changes over the night, and 'models' of SWS
- 5.4 Brain work during wakefulness
- 5.5 Increased awareness during wakefulness and subsequent sleep
- 5.6 Reduced sensory stimulation during wakefulness
- 5.7 SWS reductions in psychiatric disorders
- 5.8 SWS and ageing
- 5.9 SWS deprivation
- 5.10 Brain and behaviour during SWS
- 5.11 Cerebral restitution during SWS?
- 5.12 Sleep "substances" and immunoenhancement
- 5.13 Conclusions
6. Core and optional sleep
- 6.1 Introduction
- 6.2 Natural long and short sleepers amongst humans
- 6.3 Can the normal sleeper adapt to less sleep?
- 6.4 Sleep extension
- 6.5 Are we chronically sleep deprived?
- 6.6 The circadian timing of sleep
- 6.7 Abnormalities in the timing of sleep
- 6.8 Insomnia
- 6.9 Stage 2 sleep = optional sleep ?
- 6.10 Conclusions about core and optional sleep
7. Sleep in other mammals
- 7.1 Dolphins
- 7.2 Laboratory vs natural habitats
- 7.3 Statistical analyses of mammalian sleep
- 7.4 Sleep-the immobiliser and energy conserver for small mammals
- 7.5 More energy savings if sleep develops into a shallow torpor
- 7.6 Night- versus day-sleeping mammals
- 7.7 Food, feeding behaviour, and cerebral development
- 7.8 Encephalization
- 7.9 Conclusions so far
- 7.10 Infancy
8. REM sleep
- 8.1 Perspectives on dreaming
- 8.2 REM sleep-memory, homeostatic, sentinel and motivational theories
- 8.3 Abundance of REM sleep in early life-the ontogenetic hypothesis
- 8.4 Sleep after increased learning
- 8.5 REM sleep deprivation in animals-background
- 8.6 REM sleep deprivation, learning, and drive behaviour
- 8.7 REM sleep deprivation in humans
- 8.8 Brain protein synthesis and related findings
- 8.9 Conclusions so far about the functions of REM sleep
- 8.10 Similarities between REM sleep and wakefulness
- 8.11 Keeping cool
- 8.12 Keeping warm
- 8.13 Increasing heat production without shivering
- 8.14 Thermoregulation in REM sleep reverts to the fetal level
- 8.15 Conclusions about REM sleep
Why do we sleep ?