Restless sleep is a frequent complaint clinically and often associated with specific sleep or medical conditions. Recently, restless sleep disorder (RSD) has been identified as a new pediatric sleep disorder with core features of restless sleep and frequent large muscle movements during sleep, which are not explained by other conditions. Based on the medical literature and expert clinical experience, the task force developed a consensus diagnostic criteria for RSD and scoring large muscle group movements in children aged 6–18 years. Eight essential criteria of RSD include a complaint of restless sleep, observed large body movements during sleep, video-polysomnographic documentation of ≥5 large body movements/hour, occurrence at least thrice weekly for at least 3 months, clinically significant impairment, and differentiation from other conditions that may secondarily cause restless sleep. There is evidence to support a pathophysiology based on iron deficiency, sleep instability, and increased sympathetic activation, and treatment options include oral or intravenous iron supplementation. This review describes the key features of RSD, potential pathophysiology, and current treatment options to help diagnose patients with RSD, which has been overlooked.