Why Alzheimer’s Steals Sleep, And How Scientists Got It Back

Picture a small kitchen fire. A contained mess you could put out in seconds, except instead of a fire extinguisher, the sprinkler system kicks in and floods the entire house. That, according to a new study from the University of Kentucky, is essentially what happens inside the brains of people with Alzheimer’s disease.

For years, scientists assumed that sleep problems in Alzheimer’s came from damaged neurons or the physical clutter of amyloid plaques, the sticky protein clumps that build up in the brain. But a team led by Shannon Macauley and Nicholas Constantino has found the real culprit is something else entirely: the brain’s own immune cells, called microglia.

Microglia are supposed to be the cleanup crew, swarming in to deal with the plaques. But in doing so, they trigger a cascade of inflammation, “as if the microglia are partying all night,” as Macauley put it, that keeps the brain from settling into deep, restorative sleep.

To prove it, the researchers fitted mice with tiny EEG and EMG devices, the same kind of technology used to study human sleep, and tracked brain activity in animals genetically prone to developing amyloid plaques. Then they gave the mice a drug that temporarily wiped out about 87% of their microglia. The plaques stayed exactly where they were. But the mice got back more than two hours of sleep a night.

Even more surprising: sleep loss didn’t get progressively worse as plaques accumulated. Mice with early-stage plaque buildup lost about the same amount of sleep as mice with more than double the plaque burden months later, suggesting the very first wave of immune activity may be enough to break the sleep cycle, with little room for it to get worse from there.

Why does this matter beyond the lab? Because deep, non-REM sleep is when the brain does its housekeeping, clearing out metabolic waste, consolidating memories, repairing itself. Lose that stage and you may be feeding a vicious cycle: bad sleep worsens the brain’s ability to clean itself, which may in turn worsen the disease.

The team isn’t proposing we start wiping out microglia in humans, that’s neither safe nor practical. Instead, they’re now testing whether existing, already-approved drugs (including a diabetes medication and an anti-seizure drug) can calm overactive microglia without eliminating them, in hopes of interrupting this cycle years before memory loss ever begins.

Source: University of Kentucky, published in Alzheimer’s & Dementia (2026)

Original paper: Early microglial response to amyloid plaques drives sleep loss in Alzheimer’s disease, Alzheimer’s & Dementia (2026) 

Source: Why Alzheimer’s Steals Sleep, And How Scientists Got It Back