Abstract
Background Sleep is a fundamental human behaviour with many functions, and disruptions to sleep can lead to a variety of adverse health outcomes. Previous research suggests that age can impair sleep quality, contributing to age-related declines in health. In the current study we examine lifespan changes in self-reported sleep quality and their associations with health outcomes across four domains:Physical Health, Cognitive Health, Mental Health and Neural Health.
Methods This paper reports on analyses of a large (N=2406) sample of healthy adults (age 18–98) from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN; http://www.cam-can.com) cohort. We measured sleep quality (Pittsburgh Sleep Quality Index) and measures of Physical, Cognitive, Mental, and Neural Health. We use Latent Class Analysis to identify sleep ‘types’ across the lifespan. Using Bayesian regressions we quantified the presence, and absence, of relationships between sleep quality and health measures and how these are affected by age.
Results Using LCA we identified four sleep types: ‘Good sleepers’ (68.1% of the population, most frequent in middle age), ‘inefficient sleepers’ (14.01% of the population, most frequent in old age), ‘Delayed sleepers’ (9.28%, most frequent in young adults) and ‘poor sleepers’ (8.5% of the population, most frequent in old age). Second, we find that better sleep is generally associated with better health outcomes, strongly so for mental health, moderately for cognitive and physical health, but not for sleep quality and neural health. Finally, we find little evidence for interactions between sleep quality and age on health outcomes.
Conclusions Lifespan changes in sleep quality are multifaceted and not captured well by summary measures. Instead, we find distinct sleep subtypes that vary in prevalence across the lifespan. Second, better self-reported sleep is associated with better health outcomes, and the strength of these associations differs across health domains. Notably, the absence of associations between sleep quality and white matter suggests that previously observed associations may depend on clinical samples with pathological sleep deficiencies that do not necessarily generalise to healthy cohorts. While our measure of sleep quality is self-reported, these findings suggest that such measures can provide valuable insight when examining large, typically-ageing samples.
