Longer Single-Session Interventions may not be Better: Evidence From two Randomized Controlled Trials With Online Workers Facing Mental Health Struggles

Online self-guided single-session interventions (SSIs), which provide a complete mental health intervention in one brief experience (typically 20-30 minutes), promise to increase global access to evidence-based support. One way to expand current SSIs’ reach is to shorten them, but doing so could also compromise their effectiveness. We conducted two randomized trials to test if shortening evidence-based SSIs reduces their effectiveness among adult online workers facing mental health struggles. In study 1 (n = 262), an 8-minute SSI reduced loneliness over eight weeks more than a 23-minute version of it did (b = 2.64; d = 0.22; 95% CI 0.02, 0.41; p = .03). In study 2 (n = 1,145), a 15-minute, 9-minute, 5-minute, and 3-minute version of an SSI did not significantly differ in how much they affected depression eight weeks later (ps > 0.14). Our results suggest that longer SSIs are not necessarily more helpful than shorter ones.