Hybrid digital intervention cohort in university students: feasibility pilot study using smartphone- and smartwatch-based monitoring and ecological momentary interventions

BackgroundUniversity students often struggle to maintain healthy sleep, physical activity, and screen usage due to academic pressures and irregular schedules. Ecological momentary assessments (EMAs) and interventions (EMIs) offer real-time, context-aware opportunities to monitor and promote healthier behaviors. This pilot study aimed to evaluate the feasibility of a hybrid study design combining continuous monitoring with sequential randomized controlled trials (RCTs) evaluating EMIs targeting movement behaviors among university students. MethodsThe MOVE@NUS pilot study (September 2024 - January 2025) embedded three sequential RCTs, each targeting one behavior: sleep, physical activity, or screen time. For each RCT, participants were randomized on a 1:1:1 schedule (control, intervention 1, intervention 2). Eligible participants were first-year undergraduates, aged 18-25 years, who regularly used an iPhone and an Apple Watch. Smartwatches (primary) and smartphones (supplementary) passively and continuously tracked behaviors. EMAs (eight 3-day bursts) and web-based surveys captured self-reported behaviors and participant experience. All assessments were self-administered, and no provider assistance was involved. ResultsOf 229 students who met screening criteria, 65 enrolled (mean age 20.4 {+/-} 1.5 years; 53.8% female). Questionnaire completion was high (baseline: 100.0%, midway: 89.2%, endpoint: 86.2%). EMA engagement decreased from 88.7% (first burst) to 49.2% (final burst). Passively monitored data were obtained from 62 participants (95.4%) with a mean tracking duration of 67.8 days (range: 11 to 114). Data completeness was highest for passively captured measures of physical activity, while more participant-dependent measures, such as manually uploading screen time screenshots, showed greater attrition. Overall satisfaction was 78.9% for sleep, 70.6% for physical activity, and 60.0% for screen time. ConclusionsThis hybrid study design is feasible and acceptable among university students, with successful integration of self-reports and passive tracking. Variations in engagement and data completeness highlight areas for optimization in future large-scale digital cohort studies. Trial registrationClinicalTrials.gov ID NCT06597890 First Posted: 2024-09-19.