The DSM-5 C I ass Ifl cation of sleep-wake disorders is intended for use by general mental health and medical clinicians (those caring for adult, geriatric, and pediatric pa- tients). Sleep-wake disorders encompass 10 disorders or disorder groups: insomnia disor- der, hypersomnolence disorder, narcolepsy, breathing-related sleep disorders, circadian rhythm sleep-wake disorders, non—rapid eye movement (N REM) sleep arousal disorders, nightmare disorder, rapid eye movement (REM) sleep behavior disorder, restless legs syn- drome, and substance/medication-induced sleep disorder. Individuals with these disor- ders typically present with sleep-wake complaints of dissatisfaction regarding the quality, timing, and amount of sleep. Resulting daytime distress and impairment are core features shared by all of these sleep-wake disorders.
The organization of this chapter is designed to facilitate differential diagnosis of sleep- wake complaints and to clarify when referral to a sleep specialist is appropriate for further assessment and treatment planning. The DSM-S sleep disorders nosology uses a simple, clinically useful approach, while also reﬂecting scientific advances in epidemiology, ge- netics, pathophysiology, assessment, and interventions research since DSM-IV. In some cases (e.g., insomnia disorder), a ”lumping” approach has been adopted, whereas in oth- ers (e.g., narcolepsy), a ”splitting” approach has been taken, reﬂecting the availability of validators derived from epidemiological, neurobiological, and interventions research.
Sleep disorders are often accompanied by depression, anxiety, and cognitive changes that must be addressed in treatment planning and management. Furthermore, persistent sleep disturbances (both insomnia and excessive sleepiness) are established risk factors for the subsequent development of mental illnesses and substance use disorders. They may also represent a prodromal expression of an episode of mental illness, allowing the possi- bility of early intervention to preempt or to attenuate a full-blown episode.
The differential diagnosis of sleep-wake complaints necessitates a multidimensional approach, with consideration of possibly coexisting medical and neurological conditions.
Coexisting clinical conditions are the rule, not the exception. Sleep disturbances furnish a clinically useful indicator of medical and neurological conditions that often coexist with depression and other common mental disorders. Prominent among these comorbidities are breathing—related sleep disorders, disorders of the heart and lungs (e.g., congestive heart failure, chronic obstructive pulmonary disease), neurodegenerative disorders (e.g.,
Alzheimer’s disease), and disorders of the musculoskeletal system (e.g., osteoarthritis).
sleep (e.g., prolonged apneas or electrocardiographic arrhythmias during REM sleep; con- fusional arousals in patients with dementing illness; seizures in persons with complex partial seizures). REM sleep behavior disorder is often an early indicator of neurodegen- erative disorders (alpha synucleinopathies) like Parkinson’s disease. For all of these rea- sons—related to differential diagnosis, clinical comorbidity, and facilitation of treatment planning—sleep disorders are included in DSM-S.
The approach taken to the classification of sleep-wake disorders in DSM-S can be under- stood within the context of ”lumping versus splitting.” DSM-IV represented an effort to simplify sleep-wake disorders classification and thus aggregated diagnoses under broader, less differentiated labels. At the other pole, the International Classification of Sleep Disorders, 2nd Edition (ICSD—Z) elaborated numerous diagnostic subtypes. DSM-IV was prepared for use by mental health and general medical clinicians who are not experts in sleep medicine.
ICSD-2 reﬂected the science and opinions of the sleep specialist community and was pre- pared for use by specialists.