The correlation was also whether or not people were taking sleeping pills and whether or not they had a mutation called ApoE4, which increases the likelihood of people developing Alzheimer’s disease, said Dr. Sabia.
“The study found a modest, but I would say, somewhat important link between short sleep and risk of dementia,” said Pamela Lutsey, an adjunct professor of epidemiology and community health at the University of Minnesota who was not involved in the research. “Short sleep is very common and can therefore be important on a societal level, even if it is only marginally linked to the risk of dementia. Short sleep is something that we are in control of and that you can change. “
As with other research in the field, however, the study had limitations that prevent it from being proven that inadequate sleep can lead to dementia. Most of the sleep data was self-reported, a subjective measurement that isn’t always accurate, experts said.
At one point, nearly 4,000 participants had sleep duration measured with accelerometers, and that data was consistent with their self-reported sleep times, the researchers said. However, this quantitative measurement came late in the study, when participants were around 69 years old, which made it less useful than if it had been obtained at a younger age.
In addition, most of the participants were white and better educated and healthier than the entire UK population. And when researchers rely on electronic health records to diagnose dementia, they may have missed some cases. They also couldn’t identify the exact types of dementia.
“It is always difficult to know what to draw from such studies,” wrote Robert Howard, professor of geriatric psychiatry at University College London, one of several experts who gave Nature Communications comments on the study. “Insomnia – which probably doesn’t need anything else to think about in bed,” he added, “shouldn’t worry about heading for dementia unless you fall asleep right away.”
There are compelling scientific theories about why not getting enough sleep could worsen your risk of dementia, especially Alzheimer’s. Studies have shown that cerebrospinal fluid amyloid, a protein that clumps up in plaques in Alzheimer’s disease, “increases when you are sleep deprived,” said Dr. Music. Other studies on amyloid and another Alzheimer’s protein, tau, suggest that “sleep is important in removing proteins from the brain or limiting production,” he said.