In 1934, French researcher Henri Roger coined the term parasomnie (in English, parasomnia; from the Greek para meaning “alongside” and Latin somnum meaning “sleep”) for phenomena that occur in the transition from sleep to wake or vice versa. A parasomnia can occur during the transition between nonrapid eye movement (NREM) sleep and wake (i.e., NREM parasomnias such as sleepwalking, sleep terrors, confusional arousal, sleep-related eating disorder) or during the transition between rapid eye movement (REM) sleep and wake (i.e., REM parasomnias such as REM sleep behavior disorder [RBD], recurrent isolated sleep paralysis, nightmare disorder). A parasomnia has the following features: recurrent episodes of incomplete awakening from sleep, an inappropriate or lack of response to intervention or redirection during an episode, limited or no cognition of dream imagery and partial or complete amnesia for the event. In addition, the nocturnal disturbance is not explained by another sleep, psychiatric or medical disorder or medication/substance use. Some people experience REM parasomnias and NREM parasomnias, a condition called parasomnia overlap disorder (POD). A person with POD has a disorder of arousal (e.g., sleepwalking confusional arousal, sleep terror) and rapid eye movement sleep behavior disorder (RBD; which involves vivid, often unpleasant dreams; vocalization during sleep and sudden, often violent, arm and leg movements during REM sleep [i.e., dream-enacting behavior]).
What is a sleep cycle? Most of us know that we have several stages of sleep, but it’s important to have a good understanding of the different stages of sleep and the difference between REM sleep and NREM sleep, as well as the basics of sleep cycles.
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As we begin this journey to tackle the evolution of sleep medicine in neurology and examine the changes, it would behoove us to remind ourselves where it all started with the introduction of a man who is affectionately referred to as the “father” of sleep medicine.