Mood Monitoring in Schools: A Promising Alternative to Single-Time-Point Screening

School-based mental health screening typically relies on single-time-point assessments, which assume that students' emotional well-being is sufficiently stable for classification based on a single measurement. The present study examined this assumption by evaluating the stability of emotional well-being classifications under repeated mood monitoring. Students from two secondary schools (United Kingdom, n = 413; Australia, n = 354) completed the Brief Emotional Experience Scale weekly across six to seven weeks. Emotional well-being classifications were examined relative to a predefined low well-being threshold to assess stability across time, and a post-monitoring survey examined students' self-reported perceptions of the monitoring experience. Most students (78%) showed consistently above-threshold classifications across monitoring occasions, while a small proportion (5%) showed persistently low classifications. However, 17% of students fluctuated above and below the low well-being threshold across weeks, indicating that classification status for this group was sensitive to assessment timing. When monitoring data were aggregated using different decision rules, the proportion of students flagged as low well-being varied substantially, ranging from approximately 5% under a conservative stability-based criterion to around 12% when classifications were based on averaged monitoring scores. Classifications derived from averaged monitoring scores showed high agreement with single-time-point classifications, while identifying a partially different subset of students as low well-being, underscoring the sensitivity of threshold-based decisions to classification approach. Student feedback provided preliminary contextual insight into the acceptability of repeated monitoring under routine school conditions, with over half of respondents reporting that the process supported their emotional understanding. A substantial minority also reported greater inclination to talk with others about their well-being. Overall, the findings indicate that single-time-point screening may provide an incomplete basis for emotional well-being classification for some students, and that repeated assessment offers additional temporal context for interpreting threshold-based screening decisions.