Polysomnographic Determinants of Self-Perceived Sleep Quality at Night and During the Daytime Between Consecutive Night Shifts

Introduction: Shift work and its associated disruption of the body clock can substantially impair the quality of sleep. Impaired sleep quality can influence both physical and mental health and well-being. As such satisfaction with sleep is an important aspect of shift workers’ quality of life. However, it is not clear to what extent perceptions of daytime and night-time sleep quality are similarly informed by its structural composition. The aim of this study is to identify the features of sleep that are most important for satisfaction with night-time and daytime sleep quality so that individuals may better evaluate their own sleep and how it might be improved.

Methods: Participants (n = 131, male = 73, female = 58; aged 24.9 ± 5.1 years) completed one of three laboratory-based simulated night shift protocols. These protocols comprised series of 4 to 14 consecutive nights shifts (n = 96, 19:00h- 07:00h; n = 35, 23:00h-07:00h). All participants had 9h of time in bed (TIB) on the first night (23:00h- 08:00h) and either 7h or 7.5h of TIB for daytime sleep periods (n = 18, 08:30h-15:30h; n = 17, 14:30h- 21:30h; n = 96, 09:30–17:00) between consecutive night shifts. Sleep was recorded using polysomnography and sleep stages scored according to standard criteria. Participants rated the quality of sleep episodes from 1 (“extremely poor”) to 7 (“extremely good”). The first night-time sleep and the second daytime sleep were included for each participant in this analysis.

Results: Participants obtained more sleep during night-time sleep episodes than during daytime sleep episodes (8.0h vs 6.6h, p < .001), but maintained similar sleep efficiency— i.e., total sleep time as a proportion of time in bed— in both (88% vs 90%, p=.186). Self-perceived sleep quality did not differ between night-time and daytime sleeps (4.7 vs 4.9, p=.056). Mixed-effects models that included a “sleep type” interaction term (i.e., night-time vs daytime) revealed that the best individual predictors of self-perceived sleep quality (marginal R2 = 0.05–0.11; p < .001) were: the proportion of time awake between sleep onset and offset; wake after sleep onset; sleep efficiency; total sleep time; and the proportion of wake in the final third of TIB. These associations between more wakefulness/less sleep and poorer sleep quality did not significantly differ between sleep types.

Conclusion: Although participants obtained less total sleep during the daytime than at night, the perceived quality of each sleep was similar. Satisfaction with both daytime and night-time sleep primarily appears to be affected by total sleep time and the extent to which the sleep time is interrupted by wakefulness, more so than time spent in different stages of sleep. As such, individuals dissatisfied with their sleep quality could focus on addressing social and environmental factors that can impair sleep maintenance, such as light, noise, room temperature. Support: This paper was supported by funding from the Australian Research Council.

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Artikel online veröffentlicht:
08. Oktober 2025