In this chapter you will learn
 

• About the rhythm of sleep and waking and its neural controls
• About a shorter rhythm throughout the day, and its possible functions during sleep
• What some of the sleep disorders are and what causes them
• How researchers are tackling the problem of consciousness
• Some of the neural processes that contribute to consciousness

Chapter 15 is a discussion of sleep, consciousness, and associated issues. The chapter begins with a description of circadian rhythms and the physiological origins of the 24-hour cycle. Then rhythms of shorter duration are described, including the basic rest and activity cycle evident during the day and the cycle seen in the stages of sleep. The electroencephalogram (EEG) is described as the primary indicator of changing arousal levels during sleep and waking. Evidence for various functions of rapid eye movement and slow wave sleep are examined, followed by a summary of the brain structures involved in sleep and waking. This section concludes by covering sleep disorders and their potential causes and a discussion of sleep as a form of consciousness.  This raises the question of how we define consciousness. The second part of the chapter continues this exploration by analyzing awareness and attention as components of consciousness and continues with a discussion of how a sense of self is achieved.  The roles of body image, memory and mirror neurons as contributors to the sense of self are presented; this is followed by a discussion of disorders of self, including the effects of split-brain surgery and dissociative identity disorder.  The chapter concludes with a theoretical discussion of the nature of consciousness.