Periodic limb movement disorder (PLMD) are repetitive limb movements that occur every few seconds during sleep. It usually occurs in the legs, but can also affect the arms. The movements don't wake the child, but may cause sleep disruption. The sleep disruption may lead to daytime sleepiness symptoms. Most children and adolescents are not aware of the movements during sleep. PLMD may be associated with restless leg syndrome (RLS). Presence of PLMD may prompt further evaluation with polysomnography and lab tests for ferritin levels.