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