Sleep and Sleep–Wake Disorders

Sleep is an essential physiological function. Obtaining an adequate duration of sleep at the appropriate time is important for overall physical and mental health. This chapter will cover the multiple disorders that can disrupt sleep, ranging from an inability to sleep (insomnia) to sleeping too much (hypersomnia and narcolepsy) to sleeping at the wrong time of day (circadian rhythm sleep–wake disorders. In addition, factors that can disrupt healthy sleep will be discussed, including breathing-related sleep disorders (BRSD) and restless legs syndrome, as well as abnormal behaviors that can occur during sleep, including NREM and REM parasomnias.