Poor-Quality Sleep May Be Linked to Shrinking Brain
Study finds long-term losses in gray matter
By Tara Haelle
WEDNESDAY, Sept. 3, 2014 (HealthDay News) -- Not getting a good night's sleep might be linked to shrinkage of the brain's gray matter over time, new research suggests.
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.
However, it isn't clear whether poor sleep causes the changes in the brain, whether a shrinking brain causes poor sleep, or whether a bit of both is occurring.
"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.
After making adjustments for differences in the participants' physical activity, weight and blood pressure -- which have been shown to affect sleep quality -- the researchers compared changes in participants' brain scans and reported their findings online Sept. 3 in Neurology.
In those with poor sleep quality, the researchers saw shrinkage in one part of their frontal cortex and some atrophy, or deterioration, throughout three other parts of the brain, including parts involved with reasoning, planning, memory and problem-solving.
The study didn't test participants' thinking skills, so it couldn't prove that poor sleep or brain shrinkage was linked to poor memory or difficulty thinking. However, past research has found links between declining memory and decreases in brain volume.