- Sleep fragmentation and periodic leg movement syndrome (PLMS) have been reported in adults with iron deficiency anemia. Little is known about sleep function and daytime sleepiness in children with chronic anemia such as beta-thalassemia or congenital dyserythropoietic anemia type 1 (CDA-1). To investigate if children and adolescents who have beta-thalassemia (major or intermedia) or CDA-1 experience sleep fragmentation and objective daytime sleepiness and also to investigate if children and adolescents with beta-thalassemia have obstructive sleep apnea. Ten patients (7 males and 3 females) with beta-thalassemia (mean [SD] age, 10.4 [7.3] years), 10 patients (7 males and 3 females) with CDA-1 (mean [SD] age, 13.5 [5.1] years), and 13 healthy volunteer control children(7 males and 6 females) (mean [SD] age, 10  years) underwent nocturnal polysomnographic studies. A multiple sleep latency test was performed for 6 patients who had beta-thalassemia and 8 patients who had CDA-1. Both patient groups, that is, those who had beta-thalassemia and those who had CDA-1, had multiple arousals during sleep (mean [SD], 27.8 [11.4] events per hour and 23.8 [11.8] events per hour, respectively) compared with the control subjects (12.1 [6.6] events per hour) (P<.002). Thirty-eight percent (10.6 events per hour) of the arousals in patients with beta-thalassemia and 25% (6.0 events per hour) of the arousals in patients with CDA-1 were induced by periodic limb movements during sleep. In the control group, most (98%) arousals were spontaneous and unrelated to any definable event. The multiple sleep latency test average was 7.8 minutes for patients with beta-thalassemia (n = 6) and 10.7 minutes for patients with CDA-1 (n = 8). Five patients with beta-thalassemia and 4 patients with CDA-1 underwent a second polysomnographic study on the next night to confirm reproducibility. There was no significant change in the total number or index of arousals and no difference in the severity of the periodic limb movements during sleep compared with the results of the first polysomnographic study. Children and adolescents with beta-thalassemia or CDA-1 have evidence of impaired sleep function that is partially due to periodic limb movements during sleep and arousals that result in objective diurnal sleepiness.