Alzheimer’s Disease: Why Patients Have Extreme Daytime Sleepiness?

“It's remarkable because it's not just a single brain nucleus that's degenerating, but the whole wakefulness-promoting network.”


Patients with Alzheimer’s disease often experience a symptom of extreme daytime sleepiness. Even after having a full night’s sleep, most Alzheimer’s patients have a tendency to sleep during the day. So, why is that so? What is the cause? Well, it seems a new study has finally found an answer!

According to the study, a specific type of protein might be causing extreme daytime sleepiness in patients with Alzheimer’s disease.

The study conducted by researchers at the University of California, San Francisco (UCSF) and other institutions has shown that patients with Alzheimer’s disease have a major in brain cells in certain regions of the brain, making them sleep more.

The study was published in the journal Alzheimer’s & Dementia.

The researchers also found that an over-accumulation of a specific type of protein, called “tau protein,” causes the death of the brain cells.

Senior study author Dr. Lea Grinberg said, “Our work shows definitive evidence that the brain areas promoting wakefulness degenerate due to accumulation of tau — not amyloid protein [another protein that can become toxic in Alzheimer’s disease] — from the very earliest stages of the disease.”

The researchers found that those affected by Alzheimer’s had a higher level of tau protein in three regions that make people stay awake than those with healthy brains.

Lead study author Jun Oh said, “It’s remarkable because it’s not just a single brain nucleus that’s degenerating, but the whole wakefulness-promoting network. Crucially, this means that the brain has no way to compensate because all of these functionally related cell types are being destroyed at the same time.”

Previous research conducted by Dr. Grinberg and her team suggested that tau protein may directly impact brain degeneration in patients with Alzheimer’s disease. In that research, they found that Alzheimer’s patients who died with a higher level of tau protein had developed mood changes and sleep trouble later in their life. Dr. Grinberg said, “Our new evidence for tau-linked degeneration of the brain’s wakefulness centers provides a compelling neurobiological explanation for those findings. It suggests we need to be much more focused on understanding the early stages of tau accumulation in these brain areas in our ongoing search for Alzheimer’s treatments.”