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.
Studying sleep and brain shrinkage
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 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.
Does poor sleep affect memory and thinking skills?
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.
"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."
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.
Good sleep is important
"What this study signals to me is that [good bedtime habits] and good
sleep matters," Porsteinsson said. "Whether that has to be natural
sleep or whether we can use medications to enhance sleep has not
been answered, but it's probably best to improve your natural sleep
patterns."
Sexton made several suggestions for those hoping for better sleep.
Besides talking to a doctor about sleep problems, she recommended
having a bedtime routine and going to bed at the same time each
night.
Other tips include removing gadgets such as Smartphones and tablets
from the bedroom, not checking emails right before sleep, being
physically active during the day, avoiding caffeine late in the day and
spending time outside in the sunlight each day.
- Health24