Exploring person-centred sleep and rest-activity cycle dynamics over 6 months.

Sleep and circadian characteristics are associated with health outcomes, but are often examined cross-sectionally or using variable-centred analyses. Person-centred longitudinal research is needed to identify combined effects of sleep and circadian characteristics while allowing for change over time. We aimed to classify individuals into sleep-circadian statuses (aim 1), determine whether they transitioned between statuses over time (aim 2), and explore associated covariates and health outcomes (aim 3). Young adults (N = 151) wore smartwatches continuously for 6 months. Sleep (total sleep time, wake after sleep onset) and circadian rest-activity cycle indicators (interdaily stability, intradaily variability, relative amplitude) were derived from acceleration data and aggregated into person-means for months 1, 3, and 6. These values were entered into a latent transition model for aims 1 and 2. Multinomial logistic regressions, ANOVA, and ANCOVA addressed aim 3. Four statuses were extracted (entropy = 0.88): optimal sleepers, restless sleepers, short sleepers, and nappers. 10%-13% of optimal sleepers and 21% of restless sleepers became nappers, 7%-18% of nappers transitioned to other statuses, and 94%-100% of short sleepers remained unchanged. Males were more likely than females to be short versus optimal sleepers (p < 0.001). Restless sleepers had more physical dysfunction than nappers and short sleepers (p = 0.014, 0.022), while short sleepers reported more excessive sleepiness than optimal sleepers and nappers (p = 0.006, 0.060). This study identified four sleep-circadian statuses and found evidence for change over time. Our longitudinal person-centred approach could help inform the development of tailored diagnostic guidelines for sleep and circadian-related disorders that fluctuate within-individuals.