Dr. Sabia said the correlation was also whether people were taking sleep medication and whether or not they had a mutation called ApoE4, which increases the likelihood of people having Alzheimer’s.
“The study did find a slight, but I’d say somewhat less sleep and risk of dementia,” said Pamela Lutsay, an associate professor of epidemiology and community health at the University of Minnesota, who was not involved in the research. “Less sleep is very common and because of this, even if it is moderately associated with dementia risk, it can be socially significant. Short sleep is something that we have control over, something that you can change. “
Nevertheless, like other research in this area, the study had limitations that prevent it from proving that inadequate sleep can lead to dementia. Experts said most sleep data were self-reported, a subjective measure that is not always accurate.
At one point, about 4,000 participants had sleep duration measured by accelerometers and this data was consistent with their self-reported sleep times, the researchers said. Nevertheless, this quantitative measurement came late in the study, when participants were around 69 years old, making it less useful if it was obtained at a young age.
Furthermore, most of the participants were white and better educated and healthier than the overall British population. And in relying on electronic medical records for dementia diagnosis, researchers may have missed some cases. They also could not identify the exact type of dementia.
“It is always difficult to know what to conclude from these types of studies,” said Robert Howard, a professor of old-age psychiatry at University College London, one of the many experts who commented on the study of nature communication. “Insomnia – who probably don’t need anything else to peep in bed,” he said, adding, “Don’t worry that they’re going for dementia until they go to sleep immediately.”
There are compelling scientific theories about why very little sleep can increase the risk of dementia, especially Alzheimer’s. The study found that the cerebrospinal fluid levels of amyloid, a protein that rises in plaques in Alzheimer’s, “go up if you deprive people of sleep,” Dr. Musk said. Other studies of amyloid and another Alzheimer’s protein, Tau, show that “sleep is important for extracting proteins from the brain or limiting production,” he said.