The effects of a sleep-focused smartphone application on insomnia and depressive symptoms: a randomised controlled trial and mediation analysis.

BACKGROUND: Rates of depression are increasing among adolescents. A novel way to reduce depression is by improving sleep. We evaluated whether an app-based intervention for insomnia improved sleep and depression, and whether changes in insomnia mediated changes in depression. METHODS: We conducted a 2-arm single-blind randomised controlled trial at the Black Dog Institute in Australia. Adolescents 12-16 years experiencing insomnia symptoms were randomly allocated to receive Sleep Ninja, an app-delivered cognitive behavioural therapy program for insomnia, or to an active control group involving weekly text message sleep tips. Assessments took place at baseline, 6 weeks (post-intervention) and 14 weeks (post-baseline). Co-primary outcomes were symptoms of insomnia and depression at post-intervention (primary endpoint). Intent-to-treat analyses were conducted. The trial is registered with the Australian and New Zealand Clinical Trials Registry, number ACTRN12619001462178. RESULTS: Between October 25, 2019, and September 6, 2020, 264 participants were randomised to receive Sleep Ninja (n = 131) or to the control group (n = 133). Relative to the control group, those allocated to the intervention reported a greater reduction in insomnia symptoms at 6 weeks (95% CI: -2.96 to -0.41, d = .41) and 14 weeks (95% CI: -3.34 to -0.19, d = .39), and a greater reduction in depression symptoms at 6 weeks (95% CI: -3.46 to -0.56, d = .28) but not 14 weeks (p < 1). Change in insomnia mediated change in depression. No adverse events were reported. CONCLUSIONS: An app-delivered program for insomnia could be a practical, non-stigmatising and scalable way to reduce symptoms of insomnia and depression among adolescents experiencing difficulties getting enough good quality sleep.