Exploring person‐centred sleep and rest–activity cycle dynamics over 6 months

TL;DR

This study tracks sleep and circadian patterns in young adults over six months to identify distinct sleep types and how they change over time.

Contribution

The study introduces a longitudinal person-centred approach to analyze sleep-circadian dynamics and their transitions.

Findings

Four sleep-circadian statuses were identified: optimal sleepers, restless sleepers, short sleepers, and nappers.

Most short sleepers remained unchanged, while some optimal and restless sleepers transitioned to napping.

Males were more likely to be short sleepers, and restless sleepers reported more physical dysfunction.

Abstract

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.

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