Most people wake briefly many times during the night without realizing it.
New research suggests that the pattern of these tiny awakenings could someday help scientists spot people who are more vulnerable to Alzheimer’s disease before they notice any problems with memory.
The finding comes from researchers at the University of Liège in Belgium. They found that healthy people in late middle age who had more brief sleep interruptions also tended to carry a greater genetic risk for Alzheimer’s disease.
Alzheimer’s develops slowly. The disease may be changing the brain for years or even decades before forgetfulness, confusion, and other clear symptoms become serious enough for a diagnosis.
That long silent period creates a major challenge for doctors. By the time symptoms appear, substantial damage may already have occurred, so scientists want simple ways to recognize early changes in people who still feel well.
Sleep is one promising place to look because the sleeping brain is far from inactive. During the night, the brain moves through several stages that support memory, learning, emotional health, and normal brain maintenance.
A person does not stay deeply asleep for eight uninterrupted hours. The brain naturally moves closer to wakefulness at different times, and very short awakenings can happen without the sleeper becoming fully conscious.
Scientists call these events micro-awakenings. A person may have no memory of them in the morning, but sensitive recordings of brain activity can detect when they occur.
For the new research, the team studied more than 500 adults who were considered healthy. Their sleep was carefully recorded so researchers could measure how often their brains briefly shifted toward wakefulness during the night.
The scientists then compared the sleep results with genetic information. Instead of looking at only one gene, they used a score that estimates Alzheimer’s risk from many inherited genetic differences.
The strongest connection appeared in participants around late middle age, with an average age of 59. People with a greater inherited risk of Alzheimer’s tended to experience more micro-awakenings, while the researchers did not see the same relationship clearly in younger adults.
This does not mean that restless sleep is a diagnosis of Alzheimer’s. It does suggest that the connection between sleep and the disease may begin earlier than the memory problems that families and doctors usually notice.
One possible explanation involves a tiny brain region called the locus coeruleus. It sits deep in the brainstem and plays an important role in keeping people alert during the day and helping the brain manage the switch between sleep and wakefulness.
The locus coeruleus has attracted attention from Alzheimer’s researchers for another reason. It is among the first areas where abnormal changes involving tau, a protein strongly linked to Alzheimer’s disease, can appear.
These changes can begin surprisingly early, even though most people who eventually develop Alzheimer’s do not show symptoms until much later in life. If early changes affect the way the locus coeruleus works, they might also leave a small fingerprint in a person’s sleep.
Another possibility is that sleep disruption and Alzheimer’s risk influence each other. Poor sleep may affect processes that keep the brain healthy, while very early brain changes could also make sleep more fragmented.
Scientists have previously linked poor sleep with several forms of poor health, but sleep is complicated. Age, depression, anxiety, pain, breathing problems during sleep, medicines, alcohol, work schedules, and many other factors can change how often someone wakes.
For that reason, people should not assume that frequent waking means they are developing Alzheimer’s disease. The new research found a statistical relationship with genetic risk, not proof that micro-awakenings directly cause the disease.
The study was published in the journal Sleep by researchers from the University of Liège. Senior researcher Gilles Vandewalle said that sleep could eventually become an accessible way to help identify people who may be especially vulnerable.
One strength of the study is that the participants were healthy, allowing the researchers to look for subtle changes before diagnosed dementia could itself disrupt sleep. Using direct recordings of brain activity also gives more detailed information than simply asking people whether they think they slept well.
But important questions remain. The researchers need to follow people over time to learn whether those with more micro-awakenings actually develop Alzheimer’s more often, and other studies must confirm whether the result applies to different populations.
The findings are therefore promising, but they are not ready to become a screening test. Their real importance is that they point scientists toward a potentially useful window into the brain: the small changes that happen while a person is asleep and unaware.
If future research confirms the connection, sleep monitoring could eventually be combined with other information, such as age, family history, blood tests, or brain scans. That could help doctors recognize increased risk earlier and give researchers a better chance to study how Alzheimer’s begins before major memory loss takes hold.
If you care about Alzheimer’s, please read studies about the likely cause of Alzheimer’s disease , and new non-drug treatment that could help prevent Alzheimer’s.
For more health information, please see recent studies about diet that may help prevent Alzheimer’s, and results showing some dementia cases could be prevented by changing these 12 things.
Source: University of Liège.
