It’s always perfectly clear how essential sleep is when you try to start your day after not getting a lick of it the night before.
But becoming more tired during the daytime, especially over time, can be indicative of a larger issue, at least for older women.
A study published in the medical journal of the American Academy of Neurology followed 733 female participants with an average age of 83 over the span of five years. None of them had dementia or mild cognitive impairment at the start of the study.
Over the course of the study period, 13% of the participants developed dementia and 22% developed mild cognitive impairment, which is a condition that involves memory loss and trouble with language and judgment but doesn’t affect daily activities.)
For three days at the start and at the end of the study, participants wore wrist devices to track patterns and changes in their nighttime sleep duration and quality, daytime napping and circadian rhythm patterns.
Researchers concluded that, at least for women, increased sleepiness during the day over a five-year period is associated with double the risk of developing dementia during that period.
Researchers categorized participants into three groups: stable sleep or small improvements in sleep (44%), declining nighttime sleep (35%) and increasing sleepiness (21%).
They defined declining nighttime sleep as:
- Decreases in nighttime sleep quality and duration
- Worsening circadian rhythms
- Moderate increases in napping
Increased sleepiness was defined as:
- Increases in both daytime and nighttime sleep duration and quality
- Worsening circadian rhythms
Of the participants in the stable sleep group, 8% developed dementia by the end of the study, as did 15% of the declining nighttime sleep group and 19% of the increased sleepiness group.
After accounting for differences that could be attributed to age, education and race, and health issues such as diabetes and high blood pressure, researchers concluded that those in the increased sleepiness group were associated with double the risk of developing dementia than those in the stable sleep group.
“Sleep is essential for cognitive health, as it allows the brain to rest and rejuvenate, enhancing our ability to think clearly and remember information,” says study author Yue Leng, an associate professor with the University of California, San Francisco.
The study also notes that it only shows an association between daytime sleepiness and dementia, and the researchers highlight the need for further studies to better understand the link.
“[L]ittle 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,” Leng says. “Our study found that sleep problems may be intertwined with cognitive aging and may serve as an early marker or risk factor for dementia in women in their 80s.”
To learn more about how you can get a better night’s sleep, read “7 Sleep Tricks That Actually Work.”
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