Sudhansu Chokroverty

Chapter 28 – Motor Functions and Dysfunctions of Sleep

Publisher Summary This chapter focuses on motor functions and dysfunctions of sleep. Motor disturbances associated with sleep can be loosely sorted into two categories. In the first category, there are motor disturbances—diurnal movement disorders—present during the daytime that may have an impact on sleep, either directly through their motor effects or indirectly through a variety of other mechanisms. These are the typical movement disorders that are seen by a movement disorder specialist. In the second category, there are motor disturbances that are predominantly associated with sleep. They may be motor activity similar to what is normally found during waking hours that intrudes upon sleep or abnormal motor activity that does not occur during the wake state but is aroused by sleep. These are generally classified as sleep disorders and primarily are treated by a sleep disorder specialist. These two main categories are by no means completely unique, and it is not unusual for a patient with a disorder in one category to be seen by a specialist in the other category.

Movement Disorders in Sleep

Normal and abnormal movements in sleep have been a source of both great academic interest and clinical confusion. Nocturnal head banging (jactatio capitis nocturna) was one of the earliest-described sleep-related movement disorders, having first been mentioned in 1811. Since Manoia’s initial classification of abnormal movements in sleep as a separate category of sleep disturbances 90 years ago, a lot of progress has been made in the field. Several investigators have contributed to our understanding of these phenomena, which include rhythmic movements in sleep, hypnic jerks, propriospinal myoclonus, periodic limb movements in sleep, catathrenia, and phasic muscle movements in rapid eye movement (REM) sleep. This chapter provides a brief chronological account of discoveries and research in the field of sleep-related movement disorders.