Parasomnia

Part of speech: noun

Definitions

1. A classification of sleep disorders featuring atypical behaviors or experiences that happen during sleep, like sleepwalking and night terrors
2. A collection of disorders related to sleep that manifest through unusual behaviors or experiences, such as nocturnal acts like sleepwalking and vivid dreams
3. Sleep disorders characterized by unusual physical or mental activities occurring during sleep, such as sleepwalking or night terrors

Etymology: Parasomnia is a modern medical coinage, built from two parts: the Greek prefix "para-", meaning "beside" or, in medical use, "abnormal," and the Latin "somnus," meaning "sleep." Together they describe sleep that is disrupted by unusual behaviors or experiences rather than simply by being awake. The Greek and Latin pieces are ancient, but the combined term belongs to the language of sleep medicine, so no ancient physician used it. The word's construction mirrors a familiar pattern in clinical vocabulary, where a Greek prefix sits on a Latin root. The prefix "para-" appears in many medical terms, such as "paranoia" and "paraplegia," where it signals deviation from the normal state. Here it marks sleep that has gone off its usual course, from sleepwalking to night terrors.

Synonyms: sleep disorder, sleep disturbance, nightmare disorder, sleepwalking, REM behavior disorder