Sleep-wake disorders

**Definition:** Sleep-wake disorders are characterised by difficulty initiating or maintaining sleep (insomnia disorders), excessive sleepiness (hypersomnolence disorders), respiratory disturbance during sleep (sleep-related breathing disorders), disorders of the sleep-wake schedule (circadian rhythm sleep-wake disorders), abnormal movements during sleep (sleep-related movement disorders), or problematic behavioural or physiological events that occur while falling asleep, during sleep, or upon arousal from sleep (parasomnia disorders).