Children with autism spectrum disorders (ASDs) have much higher rates of sleep disturbance than do typically developing children. Weighted blankets are an intervention widely accepted by families to improve sleep quality for children with ASDs, but the evidence supporting their use is limited. This study was conducted at three clinical sites in England, enrolling children aged 5-16 years with a diagnosis of ASD. All children had a reported disturbance in sleep for at least 5 months prior to enrollment. Sleep disturbances included sleep latency (delay of falling asleep of at least 1 hour after "lights out") and receiving fewer than 7 hours of continuous sleep.
The investigators chose a single manufacturer to make both the weighted and the "placebo" blankets. Two different sizes were used, depending on the age and size of the child. The small weighted blanket weighed 2.25 kg, and the larger blanket weighed 4.5 kg. Control blankets were made of the same material, but plastic beads were inserted into the blanket instead of the typical steel shot. This controlled for the insulating effect of a blanket during sleep, and the embedded beads provided similar tactile stimulation but without the inclusion of the weight.
The children were randomly assigned 1:1 to begin with either the intervention or placebo blanket. During the treatment phases, the children used the blanket for 12-16 nights. After completion of one treatment phase, the children then crossed over to using the other blanket for another 12-16 nights of monitoring. During each treatment phase, parents and children (if old enough) completed sleep diaries that measured sleep latency, duration of sleep, and parental perceptions of sleep quality. Children also wore electronic devices (accelerometers) on the nondominant hand that measured movement, with still times being considered "sleep" and times of movement above predesignated thresholds being labeled as "awake." This allowed the investigators to calculate the total sleep time, which was the primary outcome of interest. The parental measures of sleep duration and quality were secondary outcomes. The parents and children also completed subjective evaluations of the acceptability of the blankets.
They enrolled 67 children in the trial, approximately 80% of whom were boys. At enrollment, more than 80% of the children experienced sleep latency, 53% experienced poor sleep maintenance, and 43% experienced both sleep problems. The final analytic cohort included 64 children; dropout was similar in both groups. The average sleep latency during treatment phases was 77.1 minutes, and the average total sleep time was 453 minutes (7.5 hours). There were no significant differences when looking at within-subject differences in total sleep time during weighted blanket vs unweighted blanket intervention periods. The total sleep time was 454.4 minutes when the children used weighted blankets compared with 457.7 minutes when using placebo blankets. Mean sleep latency was 74.3 minutes with the weighted blanket compared with 69.9 minutes with the control blanket, a difference that did not reach statistical significance. The average time awake after sleep onset (84 minutes) was virtually identical between the two groups. Parental estimates of sleep duration during weighted and unweighted blanket treatment phases did not differ. Children clearly favored the weighted blanket over the unweighted blanket when asked about general likability (48% vs 31%), and the parents believed that sleep was improved using the weighted blanket compared with the unweighted blanket (51% vs 16%). Moreover, parents judged that the weighted blanket made their child calmer (35% vs 14%) than the unweighted blanket. The investigators concluded that the weighted blankets provided no clinically measurable benefit for sleep measurements in these children, including parental assessments of sleep duration and sleep latency. However, parents and children both reported preferring the weighted blankets.
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