Poor sleep has been associated with the development of Alzheimer's disease, and this has been thought to be in part because the protein amyloid beta increases with sleep deprivation. A new study explains more.

Experiments with mice show that sleep deprivation also rapidly increases levels of the other key Alzheimer’s disease protein, tau tangles.

The work built on findings that tau is high in older people who sleep poorly, and that, when people are kept awake all night, their tau levels rise by about 50%.

When mice had tau proteins seeded in the hippocampus of their brains, those who were kept awake for long periods each day (mice are nocturnal), showed significantly greater spread of tau tangles than those mice allowed to sleep normally. Moreover, the new tangles appeared in the same areas of the brain affected in people with Alzheimer’s.

Disrupted sleep also increased release of synuclein protein, a hallmark of Parkinson’s disease. People with Parkinson’s—like those with Alzheimer’s—often have sleep problems.

All of this supports the idea that sleep directly protects against the development of Alzheimer's.

https://www.futurity.org/alzheimers-disease-sleep-tau-1966962/