Could the secret to detecting Alzheimer’s disease lie not in the complex diagnostic tests of a neurologist’s office, but in the quiet, often overlooked patterns of our nightly slumber? Researchers at the University of Liège (ULiège), with the vital support of the Stop Alzheimer’s Foundation, are currently exploring a compelling hypothesis: that subtle, seemingly innocuous changes in the way we sleep may contain early clues to neurodegenerative vulnerability years—or even decades—before the first signs of memory loss or cognitive decline become apparent.
In a significant study recently published in the scientific journal Sleep, a team from the GIGA Neurosciences institute at ULiège examined the sleep patterns of more than 500 healthy individuals. By comparing these patterns against genetic markers, the researchers have uncovered a potential connection between nighttime "micro awakenings" and an increased genetic predisposition to Alzheimer’s disease. While the research remains in its early stages and does not suggest that these sleep disturbances are a direct cause of the disease, the findings open a new, potentially non-invasive window into the early identification of those most at risk.
Looking for Alzheimer’s Clues Before Symptoms Emerge
The relationship between sleep and brain health has been a subject of intense scientific inquiry for years. Chronic sleep deprivation and poor sleep quality have long been associated with various neurodegenerative conditions. However, the study conducted at the University of Liège adds a sophisticated layer to this body of knowledge by suggesting that the biological connection between sleep and Alzheimer’s risk may begin to manifest long before any recognizable clinical symptoms appear.
Because Alzheimer’s disease is a complex condition—one that is neither purely hereditary nor entirely independent of our genetic makeup—researchers utilize a metric known as "polygenic risk." This figure summarizes the combined influence of a multitude of genes on an individual’s statistical probability of developing a specific condition. For this study, the ULiège team calculated the polygenic risk scores for more than 500 participants, all of whom were healthy at the time of the investigation.
The cohort was divided into two distinct age groups to observe how these patterns evolve over time. The majority of participants were young adults between the ages of 18 and 31, while a second, older group consisted of individuals aged 50 to 69. It is critical to note that the polygenic risk levels measured within this study remained relatively low across the board; the researchers emphasize that these metrics cannot, and do not, serve as a predictive tool for whether any specific individual will inevitably develop the disease. Rather, the study acts as a population-level investigation into biological correlations.
Tiny Awakenings During the Night
When the researchers cross-referenced these genetic risk estimates with specific characteristics of the participants’ sleep, a striking pattern emerged regarding "micro awakenings." These are defined as very brief, transient bursts of brain activity that interrupt the normal progression of the sleep cycle. Crucially, these events are so fleeting that they do not cause the sleeper to wake up fully; most people are entirely unaware that these interruptions are happening at all.
The analysis revealed a statistically significant association between a higher genetic risk for Alzheimer’s and the frequency of these micro awakenings. However, this connection was not universal across the study participants. Among the younger adult group, there was no detectable link between micro awakenings and genetic risk. The story changed, however, when the team analyzed the older cohort. In individuals aged 50 to 69, those who experienced more frequent micro awakenings consistently demonstrated a higher genetic risk score, despite the fact that all of these participants were healthy, relatively young, and entirely free of Alzheimer’s-related symptoms.
"These micro-awakenings are therefore not insignificant," explains Puneet Talwar, a researcher at the GIGA ULiège laboratory. "Our findings suggest that certain physiological profiles during sleep could promote the accumulation of proteins involved in Alzheimer’s disease, and such patterns may be associated with increased vulnerability to the condition later in life."
A Tiny Brain Region Draws Attention
To better understand why these sleep disturbances might be linked to Alzheimer’s risk, the research team turned their attention to the locus coeruleus. This is an extraordinarily small region of the brain, located deep within the brainstem and measuring roughly the size of a single grain of rice. Despite its diminutive stature, the locus coeruleus plays an outsized role in the regulation of essential functions, including wakefulness, attention, and the maintenance of sleep cycles.
"This region is notoriously difficult to observe, but it appears to play a pivotal role in the early mechanisms linked to the disease," says Gilles Vandewalle, co-director of the GIGA CRC In Vivo Imaging technology platform and a Research Director at the Fund for Scientific Research (FNRS) at ULiège.
In 2025, the research team reached a technological milestone by utilizing a state-of-the-art 7-Tesla MRI scanner at the ULiège imaging platform. This advanced, high-resolution equipment allowed the scientists to examine the locus coeruleus with unprecedented detail. The results were telling: the researchers found that specific characteristics of sleep quality—such as the speed at which a participant falls asleep and the overall depth of their sleep—were associated with the functional condition of the brainstem, even in younger participants.
Furthermore, the study found that the healthy functioning of the locus coeruleus was directly related to the quality of REM (Rapid Eye Movement) sleep, a phase of the sleep cycle that is vital for memory consolidation and cognitive maintenance. The locus coeruleus is of particular interest to the Alzheimer’s research community because it is among the very first regions of the brain where abnormal protein deposits—often considered the hallmark of the disease—begin to appear. Scientific evidence suggests these deposits may start accumulating as early as adolescence, though the exact biological significance of these early changes remains a subject of ongoing study.
Could Sleep Become an Early Alzheimer’s Marker?
Taken as a whole, the findings from the University of Liège represent a potential shift in how scientists approach the screening and prevention of Alzheimer’s disease. If sleep patterns can indeed serve as a reliable, non-invasive biomarker, they could eventually complement existing diagnostic methods to identify vulnerable individuals years before the disease manifests clinically.
"Sleep could become an accessible marker for the early identification of vulnerable individuals," adds Gilles Vandewalle. Beyond mere identification, the research team is also keen to explore the therapeutic possibilities: if we can identify these vulnerabilities early, could improving sleep quality help to prevent, or at least slow, the progression of the disease in those with a genetic predisposition?
"This research shows that sleep is not only an indicator of health, but also a potential lever for intervention," says Lucie Leroux, head of French-speaking activities at the Stop Alzheimer’s Foundation.
It is a message of both caution and hope. With more than 220,000 people in Belgium currently affected by Alzheimer’s disease, the search for early markers is a public health priority. However, the researchers are quick to clarify that their findings demonstrate statistical associations rather than a definitive causal link. These results do not prove that micro awakenings cause Alzheimer’s, nor can they be used as a diagnostic tool for an individual patient at this time.
Nevertheless, the study provides a compelling glimpse into the subtle, invisible changes that may occur in the brain decades before the disease becomes clinically visible. By shedding light on the role of the locus coeruleus and the significance of sleep quality, the work at ULiège underscores the immense value of basic research. It is through these foundational investigations that the scientific community inches closer to not only understanding the origins of Alzheimer’s but eventually finding ways to anticipate and mitigate its impact. As the team moves forward with further research to confirm and expand upon these findings, the simple act of sleep continues to prove itself as a complex and critical frontier in the fight against neurodegeneration.
