By Tara Haelle
Faster deterioration of three parts of the brain was seen in mostly older adults who had poor sleep quality, though not necessarily too little sleep. Sleep difficulties included having trouble falling asleep, waking up during the night or waking up too early.
"We spend roughly a third of our lives asleep, and sleep has been proposed to be 'the brain's housekeeper,' serving to restore and repair the brain," said lead researcher Claire Sexton, a postdoctoral research assistant at the University of Oxford in England.
"It follows that if sleep is disrupted, then processes that help restore and repair the brain are interrupted and may be less effective, leading to greater rates of decline in brain volume," she explained.
But it's just as likely, she said, that the deterioration in the brain also contributes to difficulty sleeping.
"It may be that greater rates of decline in brain volumes make it more difficult for a person to get a good night's sleep," said Sexton, adding she suspects the problems run in both directions.
While a visiting research fellow at the University of Oslo, Norway, Sexton and her fellow researchers gave brain scans to 147 Norwegian adults, average age 54, at the study's start and an average of 3.5 years later.
At the time of the second scan, the adults also filled out questionnaires about their sleep quality, including how long and how well they slept, how long it took to fall asleep, how much time in bed was spent actually asleep, how often they woke up, how sleepy they were during the day and whether they used sleeping medications. Participants took an average of 20 minutes to fall asleep and slept an average of seven hours a night, the researchers found.