Early in the nineteenth century, Frank [11, 12] presented a comprehensive classification of sleep disorders , as part of a classification of diseases of the nervous system, updating previous nosological systems [13–15]. Frank described seven classes of sleep disturbances: (1) cataphoria, a more intense and prolonged sleep than normal, which occurs in a symptomatic and an idiopathic form. Cataphoria best corresponds to hypersomnia in actual nosological systems; (2) agrypnia or insomnia, subdivided again into a symptomatic and an idiopathic form. Idiopathic insomnia (“l’agrypnie primitive”) occurs in children and adults. In adults, the disorder was classified according to its etiology into (a) inflammatory, (b) gastric, (c) arthritic, and (d) nervous types; (3) a group of disorders characterized by alterations of the appearance of sleep (“par sa manière d’être”), i.e., disorders which are grouped in actual nosological terms as parasomnias . The group includes (a) snoring, (b) jactations, cramps, and episodes of nocturnal heat (“chaleurs nocturnes”), and (c) sleep terrors (“frayeurs nocturnes”); (4) anxiety dreams (“songes effrayants”); (5) nightmare (incubus); (6) somnambulism; and finally (7) somniation, a form of sudden, sometimes periodic episodes of dream-or sleep-like behavior (gesticulation, writhing, speaking, walking, etc.)-during waking, followed by amnesia for the event. For all these disorders, Frank gave a definition, a description of symptoms, causes, diagnosis, and treatment , supplemented by an extensive bibliography, citing all available references from earlier authors.

About the same time, Hosack [22] published a syllabus containing a synopsis of the main 13 nosological systems of illnesses, published in the second half of the eighteenth and the early nineteenth century. All different sorts of sleep disorders can be found there, with varying terminology and scattered over different diagnostic classes. Table 12.2 summarizes all sleep-related disorders contained in these nosological systems, rearranged according to the categories of the actual International Classification of Sleep Disorders [23]. To get a more complete picture of the historical development , 12 more classifications of sleep disorders were added, which cover the time span from 1838 to 1970. While the selection of these 12 references is fortuitous, the aim was to include diagnostic systems from different countries. These latter entries were not drawn from comprehensive nosological systems of illnesses but from sleep-specific publications. The entries in Table 12.2 show a dominance of three diagnostic categories (insomnias, hypersomnias, and parasomnias) in the considered period; while entries in other American Academy of Sleep Medicine (AASM), diagnostic categories were rare. Abnormal movements in sleep were listed, for the first time, as a separate class of disturbances by Romagna Manoia in 1923 [24]. Most astonishing is the near absence of entries to the category of sleep-related breathing disorders (SRBD), while the lack of circadian sleep rhythm disorders is less surprising for a time when shift work was rare [25], and living conditions of the majority of people were more regular than nowadays.

Between 1800 and 1880, about 50 publications per decade on sleep disturbances appeared in the medical literature (Fig. 12.1). Publications on sleep and sleep disturbances made up a very small segment of the medical literature. There were very few scientific journals available, mainly in London and Paris. The situation changed clearly in the last third of the nineteenth century with the number of publications on sleep disturbances doubling or tripling at the end of the century. The next steep increase came in the third and fourth decade of the twentieth century, emphasizing the electrophysiological area of sleep research. Figure 12.2 displays publications schematically showing publications in four categories of sleep disorders (insomnia , hypersomnias, parasomnias, and narcolepsy) per decade. Parasomnias dominated the publications in the first six decades; whereas in the seventh decade, insomnia , hypersomnias, and parasomnias had about an equal number of publications. In the eighth decade, narcolepsy appeared as a new diagnosis category. In the past four decades, ending with the year 1950, insomnia was the leading diagnosis , followed by narcolepsy, parasomnias, and hypersomnias .

The definition of insomnia by Macfarlane [35] as “loss of sleep” and “the want of sleep” addresses two different perspectives (one empirical, the other subjective) . An important point, still discussed today, concerns the status of insomnia: Is it a symptom or a disease? The majority of authors at the end of the nineteenth and in the first half of the twentieth century considered insomnia as a symptom, similar to Macfarlane’s concept who stated: “It is not a disease, but a symptom of many diseases, differing widely in their nature and complexity, as well as gravity.” [35, p. 28]

Kroker, in his book on the history of sleep research, claimed that from 1960 onward “The diagnosis and treatment of insomnia came to rely on laboratory-based studies of sleep.” and “sleep…emerged to become a public concern by the end of the twentieth century.” [6, p. 349] Kroker further stated that insomnia was a “crucial component of the medical knowledge of sleep” (p. 349) but “if insomnia was a routine concern for clinicians, its status in terms of medical research was virtually non-existent.” “Its experience was personal, as was knowledge and diagnosis of its condition.” The physician’s role was simply to facilitate the treatment of what the patient already knew to be the problem.” (p. 350) Early writers were concerned with the search for an etiology and also for pharmacological treatment (hypnotics) of insomnia .