ABSTRACT
Parasomnias are undesirable events or experiences occurring at sleep onset, during sleep, or after partial arousals from sleep. The International Classification of Sleep Disorders, second edition, classifies parasomnias into disorders of arousal [from non-rapid eye movement (NREM) sleep] such as sleepwalking; parasomnias usually associated with rapid eye movement (REM) sleep such as REM sleep behavior disorder; and other parasomnias, such as sleep-related eating disorder (SRED) (1). Simpler movements during sleep that appear nonpurposeful, such as periodic limb movements, bruxism, and rhythmic movement disorder are classified separately under sleep-related movement disorders (see chaps. 43-49). Some abnormal behaviors at night are not generally classified under the parasomnias but need to be considered in their differential diagnosis. These include nocturnal seizures, abnormal behavior associated with arousals from sleep-disordered breathing, and nocturnal wanderings by patients with dementia. While these various groupings are helpful in classifying the disorders and understanding their pathogenesis, they are not particularly useful for the clinician faced with the problem of a patient with unusual behavior or experiences at night. This chapter will propose practical approaches for diagnosing specific parasomnias and distinguishing them from other disorders that mimic them. The clinical vignettes that follow are examples of the types of diagnostic problems to which such approaches can be applied.
