Napping during the day could be early symptom of dementia in elderly women

Napping during the day could be an early symptom of dementia in elderly women, according to researchers.

Feeling increasingly sleepy over a five-year period has been linked with double the risk of developing dementia for women in their eighties.

It is estimated that 982,000 Britons have dementia, but that figure is expected to rise to 1.4m by 2040, according to the Alzheimer’s Society.

Memory loss, difficulty concentrating and mood changes are some tell-tale signs of the condition. But the new study, published in the journal Neurology, revealed sleep problems could also be an early marker of the disease.

“Sleep is essential for cognitive health, as it allows the brain to rest and rejuvenate, enhancing our ability to think clearly and remember information,” said study author Dr Yue Leng, of the University of California, San Francisco.

“However, little is known about how changes in sleep and cognition are connected over time and how these changes relate to dementia risk in the later decades of life.”

For the study, researchers looked at 733 female participants with an average age of 83 who did not have mild cognitive impairment or dementia at the start of the study.

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The participants were followed over five years – during that time 164 participants developed mild cognitive impairment and 93 developed dementia.

They wore wrist devices to track their sleep and circadian rhythm patterns for three days at the start and end of the study.

Researchers looked at the changes in night-time sleep duration and quality, daytime napping and circadian rhythm patterns.

After five years, researchers observed large changes in sleep patterns in more than half of the participants.

The participants fell into three groups: stable sleep or small improvements in sleep; declining night-time sleep; and increasing sleepiness.

Declining sleep included a decrease in sleep quality and duration, moderate increases in napping and worsening circadian rhythms.

Increasing sleepiness included increases in both daytime and night-time sleep duration and quality, along with worsening circadian rhythms.

Researchers then looked at how these changes were linked to the risk of developing dementia.

Of those in the stable sleep group, 25 developed dementia. In the declining night-time sleep group, 39 developed dementia. In the increasing sleepiness group, 29 developed dementia.

Researchers then adjusted for age, education, race, and health factors such as diabetes and high blood pressure, and found participants in the increasing sleepiness group had double the risk of dementia compared to those in the stable sleep group.

However, no association was found in the declining night-time sleep group.

Previous studies have also highlighted that people with irregular sleep patterns may have an increased risk of developing the condition.

In that study also published in the journal Neurology in 2023, scientists assessed the health data of more than 88,000 people in the UK with an average age of 62, following them for an average of seven years. They found the risk of the neurological condition was highest for those with the most irregular sleep.

Another 2024 study looked at brain scans of nearly 600 middle-aged people and found sleeping badly aged the brain by nearly three years.

The latest study does not prove that daytime sleepiness causes dementia; it only shows an association.