While it is widely known that good sleep is important for overall health, the relationship between sleep and the risk of dementia remains elusive. A recent study indicated that better sleep is linked to improved global cognition, underscoring its potential role in maintaining cognitive function among ageing adults, according to Matthew Pase, Harvard University, Cambridge, Massachusetts, USA, and colleagues.
The researchers created the Sleep and Dementia Consortium in an attempt to advance sleep research, and develop new approaches for dementia prevention. The consortium is comprised of five prospective community-based cohorts, all of which have conducted methodologically consistent, overnight, home-based polysomnography, and neurocognitive assessments.
The research team conducted a cohort study to gain deeper insights into the associations between obstructive sleep apnoea (OSA), sleep architecture, and cognitive function. Over a span of 5 years, they tracked 5,946 American adults who were part of the five population-based cohorts within the Sleep and Dementia Consortium.
By combining across studies, the analysis aimed to address several unanswered questions. These included identifying the sleep variables most strongly linked to cognition, determining the cognitive domains most affected by sleep differences, and exploring potential systematic variations based on key factors.
The results revealed that mild-to-severe OSA was associated with poorer cognition (pooled beta coefficient per 1% increase: 0.06; 95% confidence interval [CI]: 0.11 to 0.01) in comparison to individuals without OSA. For moderate-to-severe OSA, they found similar outcomes (pooled beta: 0.06; 95% CI: 0.11 to 0.01) when compared to those without OSA.
Across various study groups, improved sleep maintenance efficiency (pooled beta: 0.08; 95% CI: 0.03–0.14) and reduced wake after sleep onset (pooled beta per 1-minute increase: 0.07; 95% CI: 0.13 to 0.01) were associated with enhanced overall cognitive function. Nevertheless, variations in sleep stages were not linked to cognition.
The findings imply that in adults without dementia, sleep consolidation and the absence of sleep apnoea may be particularly crucial for optimising cognition with ageing.
