Poor Sleep is Tied to Less Gray Matter in the Brain
Tired of never getting a good night’s sleep? Now there’s even more reason to get your Zs - not getting enough sleep may be linked to shrinkage of the brain’s gray matter, according to new research.
Studies show faster deterioration of three parts of the brain in mostly older adults who had poor sleep quality. Sleep difficulties included having trouble falling asleep, waking up during the night or waking up too early.
However, it wasn’t clear from the research whether poor sleep causes the changes in the brain or whether a shrinking brain causes poor sleep.
"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 Sexton says it’s just as likely that deterioration in the brain also contributes to sleep problems. "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.
The correlation was only with poor quality of sleep, not shorter sleep. The reduced brain size in poor sleepers was seen across all ages, but the correlation was stronger among adults over 60, the study found.
Sexton and her researchers gave brain scans to 147 Norwegian adults at the beginning of the study and again 3.5 years later. At the time of the second scan, the participants filled out surveys about their sleep quality, including how long and how well they slept, 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 any sleep medications.
After adjusting for differences in the participant’s physical activity, weight and blood pressure - which have been shown to affect sleep quality - the researchers compared changes in the participant’s blood scans over the 3.5 year period between the first and second scans.
In participants 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 actually led to a decline in mental function. However, past research has found links between decreases in brain volume and declining memory.
"We often correlate brain shrinkage with losing brain tissue, and assume that that isn't advantageous as you get older," said Anton Porsteinsson, director of Alzheimer’s disease care, research and education at the University of Rochester School of Medicine and Dentistry in New York.
"Sleep disturbance is such a common symptom among the general population, and it often becomes worse as you age," he said. "There is growing data to suggest that sleep disturbance may be a risk factor for poor outcomes in terms of brain cells and other medical issues as well."