Researchers at the University of Liege (GIGA Neurosciences) analysed the sleep of more than 500 healthy people and found that, among participants aged 50 to 69, a higher frequency of nocturnal micro-awakenings went along with a greater genetic risk of Alzheimer's disease. The same association did not appear in the younger group, aged 18 to 31. The work, supported by the Stop Alzheimer's Foundation, was published in the journal Sleep.
Micro-awakenings are brief bursts of brain activity that do not fully rouse a sleeper but can interrupt the flow of the sleep cycle. To gauge genetic vulnerability, the team calculated a polygenic risk score for each participant - a single figure summarising the combined influence of many genes on the probability of developing the disease. Alzheimer's is neither purely hereditary nor entirely unrelated to genes, which is what makes this kind of score possible in the first place.
The middle-aged participants showing this pattern were still relatively young and had no signs of the disease, which is the point that makes the finding interesting. It suggests the relationship between disrupted sleep and Alzheimer's vulnerability may take shape well before memory problems surface, and that sleep measurements could eventually help flag people worth watching more closely.
Some caution is warranted. As the researchers themselves stress, polygenic risk remains low and cannot predict who will actually develop Alzheimer's disease. The study describes a correlation in healthy volunteers, not a diagnostic test, and the authors frame early identification of vulnerable individuals as a long-term possibility rather than something available now.