Sleep Disorders

Sleep abnormalities intrigued even the earliest medical writers who detailed difficulties that people experienced with falling asleep, staying asleep, or staying awake during the day. By 1885, Henry Lyman, a professor of neurology in Chicago, classified insomnias into two groups: those resulting from either abnormal internal or physical functions; or from external, environmental influences. In 1912, Sir James Sawyer reclassified the causes as either medical; or psychic, toxic, or senile. Insomnias were divided into three categories in 1927: inability to fall asleep, recurrent waking episodes, and waking earlier in the morning than appropriate. Another reclassification, also into three categories, was made in 1930: insomnia/hypersomnia, unusual sleep-wake patterns, and parasomnias (interruption of sleep by abnormal physical occurrences). One change to that grouping was made in 1930 when hypersomnias and insomnias became separate categories.

Intense escalation of sleep study in the 1970s saw medical centers begin establishing sleep disorder clinics where researchers increasingly uncovered abnormalities in sleep patterns and events. It was during this decade that sleep disorders became an independent field of medical research and the increasing number of sleep disorders being identified necessitated formal classification.