Pediatrics published research on a survey completed by 2017 children ages 5-18 regarding activities reported during the 90 minutes before sleep time. The results indicated that television watching was the most commonly reported activity before sleep time. The participants who had a greater engagement in screen time had a later sleep onset. Participants who reported significantly greater time spent in nonscreen sedentary activities and self care had an earlier sleep onset.
Reference: Louise S. Foley, Ralph Maddison, Yannan Jiang, Samantha Marsh, Timothy Olds, and Kate Ridley Presleep Activities and Time of Sleep Onset in Children. Pediatrics 2013; 131:2 276-282; published ahead of print January 14, 2013, doi:10.1542/peds.2012-1651