How poor sleep can increase dementia risk and what to know about the links

Studies link poor-quality sleep to dementia types like Alzheimer’s disease, but experts explain why the picture might be more complex

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A recent study found that about 13 per cent of dementia cases may have roots in insomnia, and that poor sleep may be as significant a dementia risk factor as hearing loss and hypertension. Photo: Shutterstock

Published: 7:15am, 23 Mar 2026

This is the 85th instalment in a series on dementia, including the research into its causes and treatment, advice for carers, and stories of hope.

As an erratic sleeper, I worry when I see a headline such as this recent one from Science News: “Poor sleep may account for a large share of dementia cases.”

That headline topped an article about a recent study of older adults in the US. It found that about 13 per cent of dementia cases may have roots in insomnia, and that poor sleep may be as significant a dementia risk factor as hearing loss and hypertension.

But then other studies suggest differently. For example, one large analysis from the Sleep and Dementia Consortium, in which 4,600 older adults in the US were followed for up to 19 years each, found that the amount of time spent in different sleep stages – light, heavy, REM and NREM – did not neatly predict who went on to develop dementia.

Sleep is certainly important – consider how awful you feel after a bad night’s sleep. It affects our work, relationships, immunity – even our appetites. One sleep researcher says she can tell which of her colleagues had a bad night by how their canteen plates get loaded with “beige” foods – soft, crunchy or salty carbohydrates and processed items like biscuits and crisps.

We need good sleep. That is when the brain goes about housekeeping, clearing it of the toxic proteins that are hallmarks of Alzheimer’s disease.

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Decoding dementia

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How poor sleep can increase dementia risk and what to know about the links

.css-1c6uqr6{color:inherit;font-weight:inherit;font-size:inherit;font-family:inherit;line-height:inherit;overflow-wrap:break-word;}Studies link poor-quality sleep to dementia types like Alzheimer’s disease, but experts explain why the picture might be more complex

Studies link poor-quality sleep to dementia types like Alzheimer’s disease, but experts explain why the picture might be more complex