Periodic limb movements and disrupted sleep in children with sickle cell disease

Study Objectives: To describe the rate, distribution and correlates of periodic limb movements in sleep (PLMS) in children with sickle cell disease (SCD). Design: Prospective, cross-sectional. Setting: Hospital-based sleep laboratory. Participants: Sixty-four children aged 2-18 years with SCD, hemoglobin SS-type who had an overnight polysomnogram and a parent-completed Pediatric Sleep Questionnaire. Mean age was 8.4 years (SD 4.8); 50% were male. Interventions: N/A Measurements and Results: The mean PLMS index was 3.7 (6.6) and ranged from 0 to 31.8, with 23.4% of the sample having PLMS ≥ 5/h. Sleep efficiency was decreased (P = 0.03), and the total arousal index (P = 0.003) and PLMS arousal index (P < 0.001) were increased in children with PLMS ≥ 5/h compared to those with PLMS < 5/h. PLMS were most frequent in NREM stage 2 sleep and during the fourth hour of sleep. Intermovement interval duration peaked at 25-30 s. "Growing pains worst in bed" or "restlessness of the legs," suggesting restless legs syndrome (RLS), were reported in 12.5% of the total sample and were more common in children with elevated PLMS. A PLMS score for identifying elevated PLMS in children, based on items from the Pediatric Sleep Questionnaire, did not significantly predict PLMS ≥ 5/h. Conclusions: Elevated PLMS are common in children with SCD and are associated with sleep disruption and symptoms of RLS. Future research into the time structure of PLMS, their causes and consequences, and development of a disease-specific sleep disorders screening questionnaire, is needed in children with SCD.