According to a new study published in the scientific journal Alzheimer’s & Dementia, sleep deprivation in Alzheimer’s disease is not caused directly by protein plaques (amyloids) accumulated in the brain, but rather by microglia—the brain’s own immune cells. Researchers at the University of Kentucky found that hyperactive immune cells trigger a chronic inflammatory process in the brain, preventing the organ from entering the deep, restorative phase of sleep.
As part of the experiment, scientists used a specific medication to temporarily deplete approximately 87% of microglia in animal models. As a result, the subjects gained back more than two hours of restorative sleep per day—despite the amount of amyloid plaques in the brain remaining unchanged. This discovery proves that the cause of sleep disturbance is not direct neuronal damage, but rather an overreaction of the immune system, which can be managed with therapeutics.
The study also showed that Alzheimer’s pathology directly damages the deep sleep essential for clearing the brain of “toxic waste” accumulated throughout the day. The loss of this phase creates a vicious cycle that contributes to the rapid progression of the disease.
Currently, scientists are working on ways to reduce excessive microglial activity without completely destroying the cells, including through the repurposing of existing medications. According to the researchers, restoring sleep could preserve patients’ quality of life, memory, and cognitive abilities long before severe symptoms of the disease manifest.
