In 1968, in the second American Psychiatric Association’s Diagnostic and Statistical Manual (DSM-II), the only category for sleep disorders was the entry “Disorder of Sleep” [32].

In DSM-III (1980), the only two disorders of sleep included sleepwalking (somnambulism) and sleep terrors (pavor nocturnus) which were classified in the section entitled “Other Disorders with Physical Manifestations.” DSM-III-R (1987) included an expanded listing of sleep disorders in a separate section entitled “sleep disorders” [33]. It included disorders of at least 1 month in duration that were classified into two groups: the dyssomnias and the parasomnias. The dyssomnias were defined as disorders where the predominant disturbance is in the amount, quality, or timing of sleep. The parasomnias were defined as an abnormal event occurring during sleep. The categories were determined by interrater reliability using a structured interview. The dyssomnias consisted of three main disorders: insomnia disorder, hypersomnia disorder, and sleep–wake schedule disorder. The parasomnias consisted of: nightmare disorder, sleep terror disorder, and sleepwalking disorder.

The DSM-IV, published in 1994, included additional sleep disorders in part based on the ICSD (Table 23.3) [34]. A major section entitled “Primary Disorders” included in the dyssomnia category: primary insomnia , primary hypersomnia , narcolepsy, breathing-related sleep disorders, and circadian rhythm sleep disorder . Another category under parasomnias lists: nightmare disorder, sleep terror disorder, and sleepwalking disorder, as in DSM-III-R. A second major section listed “sleep disorders related to another mental disorder,” and there was an “other sleep disorders” category.