Predicting daily fluctuations in multidimensional subjective age among adults aged 19 to 84 years

Subjective age—how old individuals feel, look, behave, think, identify based on interests, and wish to be—is a multidimensional construct linked to health and wellbeing. We examined whether stable (self-perceptions of aging, aging expectations) and daily (stress, affect) factors predict six subjective age dimensions: Felt, Look, Behave, Mental, Interest, and Ideal Ages. A community sample of 209 Australian adults (19–84 years; M age = 54.56, SD = 17.49; 64.59% female) completed two 7-day diary bursts 4 weeks apart, providing 2,385–2,419 observations collected near the end of COVID-19 restrictions. Multilevel models estimated between-person (stable) and within-person (daily) associations and tested moderation by chronological age. Between persons, lower positive affect was associated with older subjective age across all dimensions except Ideal Age. More negative self-perceptions of aging predicted older Ideal Age. Age moderated the relationship between self-perceptions of aging and Interest Age: negative self-perceptions were linked to younger Interest Ages, especially among older adults. Within persons, days with higher positive affect predicted feeling younger for all except Ideal Age, whereas higher negative affect predicted older Felt Age. On days with more stress, people reported older Felt, Mental, and Interest Ages. Findings support subjective age as a dynamic, multidimensional construct in understanding aging.