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Disrupted sleep damages blood vessels in the brain and may increase the risk of dementia
Last reviewed: 03.08.2025
">A new study shows that fragmented sleep causes cellular damage to the brain's blood vessels, providing further evidence that sleep disruption predisposes the brain to dementia.
The study, published in the journal Brain, is the first to provide cellular and molecular evidence that sleep disruption directly causes damage to the brain's blood vessels and blood flow.
"We found that people with more fragmented sleep, such as restless sleep and frequent awakenings during the night, had altered balances of pericytes - cells in the brain's blood vessels that play an important role in regulating cerebral blood flow and the entry and exit of substances between the blood and the brain," said Andrew Lim, the project's principal investigator, a sleep neurologist and scientist at Sunnybrook Healthcare.
"This, in turn, was associated with more rapid cognitive decline in the ten years leading up to their death."
The researchers fitted the study participants — more than 600 older adults — with wearable devices similar to smartwatches to measure their sleep and used new gene-sequencing technologies to measure the levels of pericytes in the brain. The study participants later died and donated their brains for analysis.
"We know that in some people, sleep disturbance can precede the onset of cognitive impairment by years, and there is emerging evidence that there is a bidirectional relationship between sleep disturbance and Alzheimer's disease," adds Lim, who is also an assistant professor in the Temerty Department of Medicine at the University of Toronto.
"However, we haven't had enough evidence about the mechanisms underlying these links until now."
The results of the study indicate the following:
- Sleep fragmentation may be an important factor leading to cerebral vascular damage
- Pericytes may play a special role in mediating these effects.
- Tackling sleep fragmentation may be a way to improve brain vascular health
- Targeting pericytes may be a mechanism to prevent the deleterious effects of sleep fragmentation on cerebral blood flow and, subsequently, on Alzheimer's disease and other dementias.
"This study raises the question that changes in pericytes may be a mechanism linking sleep fragmentation to small vessel disease and cognitive decline," Lim says.
If this is confirmed in clinical trials of sleep interventions assessing pericyte markers, Lim adds, “it would highlight that sleep-targeted interventions may be effective in altering small vessel biology and cognitive decline in humans, and would also provide a rationale for aggressively treating other risk factors for cerebral small vessel disease to prevent the deleterious effects of sleep fragmentation on small vessel biology.”