This research analyzed existing data from a long-term study on nearly 8,000 British people since 1985, conducted by University College London. As part of the research project, participants reported how long they slept multiple times over 25 years. Some of them also wore sleep tracking devices to make sure they were giving accurate numbers on their sleep duration.
A team of researchers then looked for any correlation between poor sleep and a greater risk for dementia down the line.
Researchers have long suspected that there is a link between sleep and dementia risk, but they’ve been unsure where that link begins. That is, we don’t know if a lack of sleep can predispose people to dementia, or if dementia throws off people’s sleep.
The important thing about this study is that it started following the sleep patterns of people who were in their 50s, presumably before dementia had set in.