A new study found that, compared to getting seven hours of sleep a night, routinely getting six or less hours was associated with a 30 percent higher likelihood of being diagnosed with dementia nearly three decades later. The study used sleep data from surveys filled out six times by nearly 8,000 individuals between 1985 and 2016. By the end of the study, 521 people had been diagnosed with dementia at an average age of 77.
Dementia is known to disrupt sleep patterns, so it has been difficult to tease out whether insufficient sleep is a contributing cause—or an effect—of dementia. This large study from Britain analyzed data collected for about 25 years, starting when participants were young enough (around 50) that it is less likely pre-dementia brain changes had already begun.
As an observational study, this cannot prove that better sleep prevents dementia. Many factors contribute to the development of Alzheimer’s disease and other forms of dementia. There is currently no treatment for these devastating conditions. Research-backed behavioral changes—including consuming a healthy dietary pattern, engaging in regular physically activity, and getting adequate sleep—have all been associated with delaying onset or slowing progression of dementia.