Chapter 15: Sleep-Wake Disorders

Sleep disruption fundamentally impairs emotional regulation, memory consolidation, and cognitive functioning, making sleep quality an essential component of mental health assessment and intervention. The chapter establishes how circadian rhythm disturbances and abnormal sleep architecture contribute to the development and maintenance of psychiatric conditions including depression, anxiety disorders, post-traumatic stress disorder, and bipolar disorder. Understanding the neurobiological mechanisms underlying sleep regulation provides essential context for treatment selection; neurotransmitter systems including serotonin, gamma-aminobutyric acid, and melatonin pathways control sleep-wake cycling and are directly targeted by pharmacological interventions. The chapter systematically addresses major sleep-wake disorders including insomnia, obstructive sleep apnea, restless legs syndrome, and nightmare disorder, distinguishing diagnostic criteria, epidemiology, and disorder-specific treatment considerations. Pharmacological approaches range from benzodiazepines and non-benzodiazepine hypnotics to melatonin receptor agonists and antidepressants used off-label, each with distinct mechanisms of action, efficacy profiles, and risk profiles including dependence potential and residual daytime impairment. Behavioral interventions, particularly cognitive-behavioral therapy for insomnia and sleep hygiene modification, provide evidence-based alternatives or adjuncts to medication that address the underlying cognitive and behavioral factors perpetuating sleep disturbance. The chapter emphasizes clinical decision-making regarding when pharmacological intervention is warranted versus when behavioral or lifestyle modification should be the initial approach, and when referral for specialized sleep medicine evaluation is necessary for conditions like sleep apnea that require medical management beyond psychopharmacological treatment.