Women in their 80s who feel increasingly sleepy during the day over a period of five years may face double the risk of developing dementia, according to a recent study.
While the study doesn’t prove that being sleepy causes dementia, it does show a strong link between the two.
Sleep plays a crucial role in keeping the brain healthy. It gives the brain time to rest and recharge, which is important for thinking clearly and remembering things. But what happens when sleep patterns change as people age? That’s what this study set out to explore.
Researchers from the University of California, San Francisco, led by Dr. Yue Leng, examined how changes in sleep patterns affect the risk of dementia in women in their 80s. The study included 733 women with an average age of 83 who did not have any memory or thinking problems at the beginning of the study. These women were tracked over five years.
By the end of the study, 164 women (or 22%) had developed mild cognitive impairment, and 93 women (or 13%) had developed dementia. To understand sleep patterns, participants wore wrist devices that tracked their sleep and daily rhythm patterns for three days at both the start and the end of the study.
The researchers found that over five years, more than half of the women had significant changes in their sleep. They grouped the women into three categories based on how their sleep changed:
– Stable sleep or slight improvement (44%)
– Declining nighttime sleep (35%)
– Increasing sleepiness during both day and night (21%)
The “declining nighttime sleep” group saw a drop in sleep quality and sleep time at night. They also took more naps and had more irregular sleep-wake cycles. The “increasing sleepiness” group experienced longer sleep both at night and during the day, but also had worse sleep rhythm patterns overall.
When researchers looked at the risk of dementia, the group with increasing sleepiness had the highest risk. In that group, 19% developed dementia. That’s compared to 8% in the stable sleep group and 15% in the declining sleep group.
After taking into account other factors like age, education, race, diabetes, and high blood pressure, the researchers found that women in the “increasing sleepiness” group had twice the risk of developing dementia compared to those in the stable sleep group. Interestingly, the group with declining nighttime sleep didn’t show a significantly higher risk.
Dr. Leng explained that sleep, napping, and our daily body rhythms can change a lot even in just five years. This means it’s important to look at all parts of sleep, not just nighttime sleep, when studying brain health in older adults.
One limitation of the study is that most of the participants were white, so the results might not apply to all racial or ethnic groups. More diverse studies are needed in the future.
The research was funded by the U.S. National Institutes of Health and the National Institute on Aging.
The study is published in Neurology.
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