ABSTRACT
This chapter is intended to provide the reader with an overview of consciousness, the causes of disturbed consciousness, and the phenomena associated with altered consciousness including sleep, dreams and their theories, induced conditions such as hypnosis and meditation, and the effect of psychoactive drugs. The sleep section will include a review of the functions of sleep, the circadian rhythm, the neurobiology of sleep, the regulation of sleep, the stages of sleep, the effects of age on sleep, the effects of sleep deprivation, a clinical assessment of sleep, and a discussion of sleep disorders. The psychoactive drugs section will discuss depressants (alcohol, opiates and opioids, benzodiazepines, barbiturates, and inhalants), stimulants (caffeine, nicotine, amphetamines, and cocaine), hallucinogens, and other psychoactive drugs (cannabis and ecstasy).
