Could the secret to detecting Alzheimer’s disease lie not in complex cognitive tests or invasive procedures, but in the subtle, rhythmic patterns of our nightly slumber? Researchers at the University of Liège (ULiège), with the backing of the Stop Alzheimer’s Foundation, are currently exploring this provocative question. Their latest work suggests that the sleeping brain might act as an early warning system, harboring hidden clues to neurodegenerative vulnerability years—or even decades—before the first signs of memory loss or cognitive decline emerge.
In a study published in the journal Sleep, a team of scientists from the GIGA Neurosciences institute at ULiège meticulously analyzed the sleep patterns of more than 500 healthy individuals. By comparing these patterns with the participants’ genetic profiles, the researchers uncovered a compelling correlation: among middle-aged adults, frequent nighttime "micro-awakenings" were significantly linked to a higher polygenic risk for developing Alzheimer’s disease. Interestingly, this specific relationship was absent in younger participants, suggesting that as we age, the brain’s ability to maintain a stable sleep architecture may become a critical indicator of long-term neurological health.
Seeking Alzheimer’s Clues Before the Onset of Symptoms
For years, the scientific community has grappled with the complex relationship between sleep disturbances and neurodegenerative diseases. While it has long been understood that sleep quality often deteriorates in patients already suffering from Alzheimer’s, the ULiège study shifts the focus toward the "pre-symptomatic" phase. The research implies that the biological connection between disrupted sleep and Alzheimer’s risk may be established long before a patient experiences any noticeable clinical symptoms.
Because Alzheimer’s disease is a multifactorial condition—influenced by a delicate interplay of genetics, environment, and lifestyle—it is rarely the result of a single gene mutation. To navigate this complexity, the researchers calculated a "polygenic risk score" for each of the 500 participants. This score functions as a summary, aggregating the combined influence of various genetic variants on an individual’s susceptibility to the disease. The study cohort was primarily composed of young adults aged 18 to 31, with a secondary group of middle-aged individuals aged 50 to 69.
The researchers were careful to emphasize that these polygenic risk scores remain relatively low in healthy populations and cannot be used to predict whether a specific individual will inevitably develop the disease. Rather, these scores provide a statistical framework for understanding relative vulnerability. By mapping these genetic risk estimates against objective sleep data, the team began to see a distinct pattern emerge.
The Significance of Nighttime Micro-Awakenings
The analysis highlighted a particular phenomenon: nighttime micro-awakenings. These are brief, fleeting bursts of neural activity that interrupt the normal progression of sleep cycles. Unlike a full awakening, where a person might toss and turn or become consciously aware of their surroundings, these micro-awakenings are often so brief that the sleeper remains unaware they have occurred. However, they can fragment the quality of restorative sleep.
While these disruptions were common across all age groups, the implications differed significantly based on age and genetic risk. In the younger cohort, there was no observable link between these micro-awakenings and the polygenic risk of Alzheimer’s. However, the data told a different story for the older participants. Among those aged 50 to 69, a higher frequency of these tiny, silent interruptions was strongly associated with a higher genetic risk for the disease, even though these individuals were entirely healthy and showed no signs of cognitive impairment.
"These micro-awakenings are therefore not insignificant," notes Puneet Talwar, a researcher at the GIGA ULiège laboratory. According to Talwar, certain biological profiles may facilitate the accumulation of toxic proteins known to be involved in the progression of Alzheimer’s disease. In these cases, fragmented sleep may be more than just a nuisance; it could be a marker of an underlying vulnerability that, over time, increases the risk of neurodegeneration.
A Tiny Brain Region Takes Center Stage
To better understand the biological mechanisms behind these findings, the research team focused their attention on a remarkably small but powerful region of the brain: the locus coeruleus. Located deep within the brainstem and roughly the size of a single grain of rice, the locus coeruleus is a command center for the brain’s arousal systems, playing a vital role in regulating wakefulness, attention, and the depth of sleep.
"This region is difficult to observe, but it appears to play a role in the early mechanisms linked to the disease," explains Gilles Vandewalle, co-director of the GIGA CRC In Vivo Imaging technology platform and a Research Director at the Fund for Scientific Research (FNRS).
The researchers leveraged advanced technology to peer into this elusive structure. In 2025, using the high-precision 7-Tesla MRI scanner at the ULiège imaging platform, the team was able to visualize the locus coeruleus with unprecedented clarity. The findings were striking: the structural integrity and healthy functioning of the locus coeruleus were closely tied to the quality of REM (Rapid Eye Movement) sleep, a stage of the sleep cycle essential for memory consolidation and emotional regulation. Furthermore, these characteristics were already associated with the condition of the brainstem in young adults, suggesting that the foundations of sleep health—and perhaps disease vulnerability—are set early in life.
The locus coeruleus is of particular interest to Alzheimer’s researchers because it is one of the very first regions of the brain where abnormal protein deposits begin to aggregate. Some evidence suggests that these pathological changes may start as early as adolescence, decades before the disease manifests as memory loss. While the precise nature of these early shifts remains a subject of ongoing study, the link between the locus coeruleus, sleep quality, and genetic risk is becoming increasingly difficult to ignore.
Could Sleep Become a Future Marker for Screening?
The implications of this research are far-reaching, potentially opening new doors for Alzheimer’s screening and preventative medicine. If sleep architecture can be reliably linked to neurological vulnerability, then analyzing sleep patterns could eventually complement existing diagnostic tools to identify at-risk individuals long before they reach the point of clinical diagnosis.
"Sleep could become an accessible marker for the early identification of vulnerable individuals," says Gilles Vandewalle. By identifying these individuals earlier, medical professionals might be able to offer more targeted interventions, lifestyle modifications, or even future therapeutic treatments aimed at delaying the onset of the disease.
The research team is now looking toward the possibility of whether improving sleep quality could act as a protective measure, slowing down the progression of disease markers 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," adds Lucie Leroux, head of French-speaking activities at the Stop Alzheimer’s Foundation.
Despite the promise of these findings, it is essential to maintain a measured perspective. Currently, more than 220,000 people in Belgium are living with Alzheimer’s disease, and the quest for a cure or an effective early-warning system remains a global health priority. The current data from ULiège reveals statistical associations rather than definitive proof of cause and effect. Sleep patterns are influenced by a multitude of factors, and the presence of micro-awakenings does not necessarily mean a person will develop Alzheimer’s.
Further research is required to confirm these preliminary findings and to determine how sleep monitoring might be standardized for clinical use. Nevertheless, the study provides a vital glimpse into the hidden, long-term changes that may occur in the brain years before Alzheimer’s becomes clinically visible. By deepening our understanding of how the brain navigates the night, scientists are moving one step closer to the ultimate goal of identifying, understanding, and one day anticipating this devastating disease. The value of this basic research lies in its ability to illuminate the path toward earlier, more effective intervention, turning the once-mysterious landscape of the sleeping brain into a window for better neurological health.
