The prevalence of major depression is approximately 4 percentage (%) to 8% in adolescents, with the highest incidence of MDD in child onset depression occurring during mid- to late adolescence (that is, 14 to 18 years of age). Seltorexant (JNJ-42847922) is a potent and selective antagonist of the human orexin-2 receptor (OX2R) that is being developed for the treatment of adjunctive treatment of MDD with insomnia symptoms (MDDIS).The study will be conducted in 3 phases: a screening phase (up to 30 days prior to first dose administration), a double-blind (DB) treatment phase (6 weeks), and a follow-up phase (up to 2 weeks including a telephone consult and on-site follow-up visit. The total study duration for each participant will be up to 12 weeks. Efficacy, safety, pharmacokinetics, and biomarkers will be assessed at specified time points during this study. The hypothesis for this study is that the safety, tolerability, and pharmacokinetics in the adolescent MDD population. There is no formal statistical hypothesis testing due to the exploratory and descriptive nature of this study.