The aim of this pilot study was to explore the feasibility and proof of concept of triple chronotherapy (TCT) as a nonpharmacological adjunctive treatment in the acute management of depression in the adolescent population. Thirty-one adolescents with nonpsychotic moderate-to-severe depression were included in the study. The 4-day TCT intervention comprised one night of sleep deprivation followed by 3 days of sleep phase advancement and daily bright light therapy. Primary outcomes were feasibility and depression, as measured by the Hamilton Depression Scale-17 (HAMD-17). Secondary outcomes included severity of illness, anxiety, self-harm, insomnia, and suicidality. Twenty-nine (94%) adolescents completed the 4-day TCT intervention. Twenty-six (84%) of the 31 enrolled patients experienced a reduction in depressive symptoms of at least 50% from baseline; 24 (77%) achieved remission, defined as a HAMD-17 score less than 8. The mean depression score was severe before the start of the intervention ( \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $$\overline X$$ \end{document} = 21.8 ± 3.8) and dropped below the remission threshold by day 4 ( \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $$\overline X$$ \end{document} = 4.4 ± 5.1; p < 0.001); the mean depression score was mild at 1 week (n = 17; \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $$\overline X$$ \end{document} = 9.3 ± 5.2; p < 0.001) and 1 month (n = 10, \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\usepackage{upgreek}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $$\overline X$$ \end{document} = 7.8 ± 5.2; p < 0.001). Severity of illness scores according to the Clinical Global Impressions severity subscale improved from a mean of 5.3 at baseline to 3.1 following the TCT intervention (p < 0.0001); the effect was sustained through the 1-week postdischarge and the 1-month follow-up. Secondary outcomes showed significant improvement following the 4-day TCT intervention; improvement was sustained through the 1-week and 1-month follow-up periods. This pilot study determined TCT to be a feasible, safe, rapid, and potentially effective adjunctive treatment for depression in the adolescent population.