The REST (Randomised Evaluation of Sleeping with a Toy or comfort item) Trial: An online, randomised trial of comfort item use on sleep quality in children

Abstract Sleep is essential for children’s health and development, yet sleep problems are common worldwide. Comfort items such as soft toys or blankets are widely used to promote independent sleep, but their effects have not been evaluated in a randomised controlled trial (RCT). The REST trial emerged from a child-led citizen-science study (The Kid’s Trial) where children co-created and designed the trial. Therefore, this paper had two aims, to assess whether sleeping with a comfort item affected children’s sleep; and to assess the feasibility of conducting an online, child-led citizen-science RCT. The REST (Randomised Evaluation of Sleeping with a Toy or comfort item) trial was an online two-arm, parallel-group, superiority RCT. Children, aged 7 to 12 years, were randomised (1:1) to either sleep with a self-chosen comfort item (‘Try-it-Out’ group) or refrain from using one (“Wait-and-See” group) for one week. The primary outcome was sleep-related impairment (SRI; PROMIS Pediatric Short Form v1.0 SRI 4a). The secondary outcome was overall sleep quality (Single Item Sleep Quality Scale, SQS). Analyses followed an intention-to-treat principle using mixed-effects models adjusted for baseline measures. A total of 139 children from 11 countries were randomised (mean age: 9.8 years; 45% female); 101 children (73%) completed post-test measures at one week. The adjusted mean difference (Intervention minus Control) in SRI T-scores was -0.53 (95% CI: -3.40 to 2.34; p = 0.714), equivalent to approximately -0.05 SD on a scale where 10 points = 1 SD. This indicated a trivial effect, well below the minimal important difference (MID) of 3 points. The adjusted mean difference in SQS was 0.28 (95% CI: 0.01 to 0.55; p = 0.040), suggesting a small and uncertain difference in favour of the intervention group. However, this result was not supported in subsequent sensitivity or exploratory subgroup analyses. No adverse events were reported. Sleeping with a comfort item for one week did not influence sleep-related impairment. A small statistically significant difference in perceived sleep quality was observed in the primary analysis, but was not sustained in the per-protocol analysis. Together, these findings suggest that any benefit of comfort items for sleep is small and uncertain. The trial demonstrated that children can meaningfully engage in online, citizen-science research, supporting the feasibility of child-led RCTs. Trial registration ISRCTN13756306 (registered 10 January 2025)