Worldwide, about 50 million people suffer from dementia and there are almost 10 million new cases each year, according to the World Health Organization.
A major 30-year study by University College London (UCL) has drawn a clear conclusion: those who regularly fail to get at least six hours of sleep are almost a third more likely to develop dementia , compared to those with a normal duration of sleep. Thus, not getting enough sleep can increase the risk of developing dementia.
The research used data from 7,959 British adults, with a follow-up from 1985 (when the age range of the participants was 35 to 55 years) to 2015, allowing the researchers to measure sleep duration at the ages of 50, 60 and 70 years.
People who slept 7 hours or more had the lowest incidence of dementia, and there was no clear evidence of a link between longer-than-normal sleep duration and dementia (although some other studies have found such an association as well).
It is worth clarifying that studies like this are only observational, meaning that the link discovered is only a correlation between short sleep and increased risk , not a causal mechanism.
“More studies, including more people with prolonged sleep, will be needed to understand the role of sleep duration in dementia risk,” say the authors, publishing their results in the journal Nature.
Referencia: Sabia, S., Fayosse, A., Dumurgier, J. et al. Association of sleep duration in middle and old age with incidence of dementia. Nature Communications 12, 2289 (2021). https://doi.org/10.1038/s41467-021-22354-2
