Iron deficiency (ID) and restlessness are associated with sleep/wake-disorders (e.g., restless legs syndrome (RLS)) and neurodevelopmental disorders (attention deficit/hyperactivity and autism spectrum disorders (ADHD; ASD)). However, a standardized approach to assessing ID and restlessness is missing. We reviewed iron status and family sleep/ID history data collected at a sleep/wake behavior clinic under a quality improvement/quality assurance project. Restlessness was explored through patient and parental narratives and a ‘suggested clinical immobilization test’. Of 199 patients, 94% had ID, with 43% having a family history of ID. ADHD (46%) and ASD (45%) were common conditions, along with chronic insomnia (61%), sleep-disordered breathing (50%), and parasomnias (22%). In unadjusted analysis, a family history of ID increased the odds (95% CI) of familial RLS (OR: 5.98, p = 0.0002, [2.35–15.2]), insomnia/DIMS (OR: 3.44, p = 0.0084, [1.37–8.64]), and RLS (OR: 7.00, p = 0.01, [1.49–32.93]) in patients with ADHD, and of insomnia/DIMS (OR: 4.77, p = 0.0014, [1.82–12.5]), RLS/PLMS (OR: 5.83, p = 0.009, [1.54–22.1]), RLS (OR: 4.05, p = 0.01, [1.33–12.3]), and familial RLS (OR: 2.82, p = 0.02, [1.17–6.81]) in patients with ASD. ID and restlessness were characteristics of ADHD and ASD, and a family history of ID increased the risk of sleep/wake-disorders. These findings highlight the need to integrate comprehensive blood work and family history to capture ID in children and adolescents with restless behaviors.