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. 2021 Aug 16;64(11):2367–2377. doi: 10.1007/s00125-021-05541-0

Table 1.

Definitions based on ICSD-3 and prevalence of sleep disorders in the general population

Sleep problem Definition of sleep disorder based on ICSD-3 Prevalence in general population (%)a
Insomnia Disorder characterised by a dissatisfaction in quality or quantity of sleep resulting in significant daytime distress. Insomnia is associated with problems initiating or maintaining sleep, frequent awakenings and the inability to return back to sleep. These complaints occur despite adequate opportunity and circumstances to sleep. 10
Sleep-related breathing disorders Group of disorders characterised by symptoms such as snoring, fatigue, insomnia or subjective respiratory disturbances, or associated medical or psychiatric disorders in combination with ≥5 predominantly obstructive respiratory events per h of sleep, or ≥15 obstructive respiratory event per h (even in absence of symptoms). This diagnosis can be further subdivided into OSA disorders, central sleep apnoea syndromes, sleep-related hypoventilation disorders and idiopathic central alveolar hypoventilation. 3–7
Central disorders of hypersomnolence Group of disorders characterised by subjective excessive daytime sleepiness that cannot be explained as a result of another sleep–wake disorder, resulting in daily occurrences of an insuppressible need to sleep or daytime lapses into sleep. This disorder group includes narcolepsy, idiopathic hypersomnia, insufficient sleep syndrome, and hypersomnias due to medical disorders, medication or substance and psychiatric disorder 0.02–0.18
CRSWDs The disorders belonging to this group include delayed and advanced sleep–wake phase disorder, irregular sleep–wake rhythm disorder, non-24 h sleep–wake rhythm disorder, shift-work disorder, jet-lag disorder and circadian sleep–wake disorders not otherwise specified. The disorders are characterised by a chronic or recurrent pattern of sleep-disruption primarily caused by a change in the endogenous circadian timing system or misalignments between the endogenous circadian rhythm and the socially desired rhythm, resulting in insomnia or excessive sleepiness. It is associated with distress or functional impairment over a period of at least 3 months (except for jet-lag disorder). 7–16
Parasomnias Parasomnias can be divided into NREM-related parasomnias, REM-related parasomnias and other parasomnias. NREM-related disorders include recurrent episodes of incomplete awakening, with abnormal responsiveness, limited or no memory or dream report, and at least partial amnesia for the episode. REM-related parasomnias occur as a consequence of state dissociation between REM sleep and being awake. 3–17
Sleep-related movement disorders Group of disorders characterised by simple, often repeated movements during sleep. Diagnoses include RLS, PLMD, REM sleep behaviour disorder and others 5–10

aData from [79]

ICSD-3, International Classification of Sleep Disorders, third edition; NREM, non-rapid eye movement