A study by Monash University published in JAMA Network Open has found that good quality sleep and the absence of sleep apnoea are associated with better cognitive function.
The study investigated 5946 adults in the USA in five independent community-based cohorts involved in an overnight sleep study and neuropsychological assessments.
It found that better sleep quality and the absence of sleep apnoea in adults aged 58-89 who had not experienced stroke or dementia were associated with better cognition over five years of follow-up.
Individual differences in the composition of sleep, such as the time spent in light sleep, deep sleep, and REM sleep, were not associated with cognition.
“These findings suggest that in adults without dementia, sleep consolidation and the absence of sleep apnoea may be particularly important for optimising cognition with ageing,” the researchers wrote.
Participants in this community-based study did not present with any specific sleep complaints, so the association between even mild obstructive sleep apnoea and poorer cognition is an important observation.
Associate Professor Matthew Pase from the Turner Institute for Brain and Mental Health says the findings suggest that the role of interventions to improve sleep for maintaining cognitive function requires investigation.
“At least half our sample had evidence of at least mild obstructive sleep apnoea,” he said.
“I think the most interesting finding is that participants that have mild to severe sleep apnoea had worse cognition, so they had worse thinking and memory performance, for example.
“This is significant because there have been some studies that have shown relationships between obstructive sleep apnoea and poor cognition, but they’ve genuinely relied on people with a diagnosis.
“The take-home is that our findings suggest different elements of sleep are important for cognitive health, particularly the quality of someone’s overnight sleep and whether or not they have sleep apnoea.”
Associate Professor Pase says that good sleep is essential for health, yet associations between sleep and dementia risk remain “incompletely understood”.
“Most research on sleep and cognition has used subjective reports of sleep or rest-activity patterns,” he said.
“A major strength of the current study was the use of objective overnight sleep studies in such a large number of participants.”