A 25-year study out of Britain comes with a clear takeaway for those in or entering middle age: Don't scrimp on sleep. Researchers followed 8,000 people and found that 50-year-olds who got by on six hours of sleep or less per night had a 22% higher risk of developing dementia later in life than those who slept for seven hours, reports the Wall Street Journal. The figure increased to 37% for 60-year-olds. As the New York Times notes, the study in the journal Nature Communications cannot prove a cause-and-effect—that too little sleep leads to dementia. It's even possible that the reverse is true, that very early symptoms of dementia (such as the accumulation of proteins) might be leading to sleep trouble. But the bottom line is to be aware of a possible connection.
"Even though we can't say sleep duration has a causal impact on dementia, it would be good to encourage good sleep hygiene," says Séverine Sabia, an epidemiologist at the French National Institute of Health and Medical Research and lead author of the study. Among other things, people should put away their electronic gizmos about half-hour before going to bed, Sabia suggests. The findings make sense to a researcher at the Centre for Discovery Brain Sciences in Scotland who was not involved in the study. "Sleep is important for normal brain function and is also thought to be important for clearing toxic proteins that build up in dementias from the brain," Tara Spires-Jones tells CNN. One potential caveat is that participants self-reported their sleep totals, which raises questions about accuracy. (Read more dementia stories.)