- New research suggests that poor sleep quality among the elderly can cause protein buildup in their brain, putting them at risk for Alzheimer’s disease.
- While past studies have shown a relationship between poor sleep and brain changes, this study is the first to show that reduced slow-wave sleep boosts tau levels in early Alzheimer’s.
- Aside from memory decline, sleep deprivation also causes other health issues like obesity, diabetes, heart disease, or stroke.
While having trouble falling asleep and waking up frequently during the night are natural parts of the aging process, studies suggest these issues are also seen as a risk for Alzheimer’s disease.
Scientists at Washington University School of Medicine in St. Louis suggests that certain brain proteins called tau that are linked with Alzheimer’s disease rise as older people spend less time in slow-wave sleep-the sleep stage marked by deepest sleep believed to be essential for memory consolidation.
“Our project is the first to show an association between slow-wave sleep and tau in very early Alzheimer’s disease,” said lead study author Dr. Brendan Lucey, director of the Washington University Sleep Medicine Center.
As Alzheimer’s disease progresses, the tau protein, which creates tangles in brain regions critical for memory, and another called amyloid beta slowly expand all over the brain. However, sleep can flush out these memory-robbing proteins.
“Research shows that during sleep the brain can shrink substantially as it clears built-up toxins, tau, and amyloid among them,” Menlo Park Psychiatry & Sleep Medicine founder, Dr. Alex Dimitriu, told Healthline.
What research yields
For the study that took one week, 119 participants aged 60 or older with mild or no cognitive decline were asked by the researchers to keep track of their nighttime sleep sessions and daytime napping while in their homes. Each was given a portable brain-wave monitor and a wrist-worn movement tracker to wear, and were closely monitored.
The amyloid beta and tau levels in the brain as well as the spinal fluid of the participants were also measured in the trial.
After taking factors such as age, gender and movement while sleeping into account, the study showed a relationship between decreased slow-wave sleep and higher tau protein in the brain alongside a higher ratio of tau to amyloid beta in spinal fluid.
Poor sleep impacts health
Loss of even a half night’s sleep can impair brain function, according to the National Sleep Foundation.
Dimitriu noted that this may be because the brain’s waste-clearing system is specifically active during slow-wave sleep, which often occurs in the first half of the night.
He explained that older people with dementia often experience sundowning, a symptom where mental processes and awareness slow down throughout the day. “This may be a direct consequence of the buildup of these toxins during the day.”
Americans tend to skip sleep at night studying, working or socializing. In fact, between 20 to 44 percent of people in the US sleep less than seven to eight hours each night, per the Centers for Disease Control and Prevention (CDC).
But lack of sleep often leads to risks of developing serious health complications.
“Aside from a buildup of toxins, insufficient sleep can also affect mood, memory, metabolism, and the immune system,” Dimitriu said.
Here are specific health consequences resulting from poor sleep.
Insufficient sleep decreases leptin levels, a hormone that alerts the brain that a person has eaten enough. It can also ramp up the hunger hormones called ghrelin. And even if a person is already full, poor sleep could still bring on food cravings.
A study on short-term sleep restriction revealed that healthy participants who were made to sleep four hours each night, were observed to process glucose more slowly than when they were allowed to sleep for up to 12 hours.
High Blood pressure
Research finds that less than six hours of sleep can lead to hypertension or even heart disease or stroke.