Periodic limb movements in REM sleep: A periodically concerning phenomenon.

Periodic limb movements of sleep (PLMS) are involuntary, sleep-related phenomena characterized by periodic episodes of repetitive, stereotypical movements of the limbs. The presence PLMS increases with age but are frequently comorbid with other sleep disorders and other medical, neurologic, and psychiatric disorders, and can be triggered by medications and psychoactive substances. PLMS typically occur during non-rapid eye movement sleep and are generally absent during rapid eye movement (REM) sleep, with exception of patients with REM behavior disorder (RBD). However, even in the absence of RBD, PLMS are sometimes noted in REM sleep, without a clear explanation or etiology. This systematic review will focus on what is known about PLMS, as they relate to REM sleep phenomenon: PLMS in RBD, in REM sleep without atonia, and in various sleep and neurologic will be discussed.