Chapter 23: Sleep-Wake Disorders

Key neurotransmitter systems involved in sleep regulation, including gamma-aminobutyric acid, serotonin, and orexin, are explained in detail to provide understanding of how neurochemical imbalances contribute to various sleep disorders. The diagnostic classification systems of the DSM-5-TR and ICD-11 are presented to help clinicians identify and categorize sleep-wake disorders into distinct groups: insomnia disorder, hypersomnolence disorder, narcolepsy, breathing-related sleep disorders including obstructive and central sleep apnea, circadian rhythm sleep-wake disorders, parasomnias such as nightmare disorder and rapid eye movement sleep behavior disorder, and restless legs syndrome. Insomnia disorder, recognized as the most prevalent sleep complaint in clinical settings, is examined through the lens of hyperarousal theory and the cognitive-behavioral perpetuation cycles that maintain the disorder. Narcolepsy is discussed as a chronic neurological condition characterized by uncontrollable sleep attacks, cataplexy episodes, hypnagogic and hypnopompic hallucinations, and deficient hypocretin neurotransmission. Sleep-related breathing disorders are analyzed with emphasis on their serious cardiovascular and neurocognitive consequences. Circadian rhythm misalignment disorders are explored as conditions arising from conflict between internal biological timing and external social schedules. The chapter also addresses developmental considerations including pediatric sleep disturbances and age-related sleep changes in older adults, as well as cultural variations in sleep expectations and practices. Assessment methods including sleep diaries, actigraphy devices, and polysomnographic testing are described alongside clinical interviewing techniques that identify psychiatric comorbidities such as depression, anxiety disorders, post-traumatic stress disorder, and substance use disorders. Treatment approaches are presented as multimodal interventions combining cognitive-behavioral therapy for insomnia, sleep hygiene optimization, light-based therapies, pharmacological agents including hypnotics and melatonin receptor agonists, positive airway pressure devices, and behavioral management of parasomnias. The chapter emphasizes public health significance by connecting untreated sleep disorders to increased accident risk, cardiometabolic disease development, and diminished quality of life across populations.