Doing This at Night Can Spike Your Dementia Risk, New Study Says

Could this be affecting your cognitive health?

Every night as you drift off to dreamland, the quality of your sleep impacts your health, and also serves as a reflection of it. By now, most of us are aware that having chronically poor sleep can cause certain health problems and tip you off to others, but fewer among us recognize some of the subtler signs that our slumber may be trying to send us. Now, a new study is highlighting how one minor change in your sleep patterns could be a sign of increased dementia risk—and no, it's not insomnia (though this, too, is a red flag). Read on to learn how one nightly habit may spike your odds of developing dementia, and why experts believe the two are linked.

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Many people diagnosed with dementia experience sleep disturbances.

woman with insomnia, signs you need a new mattress

Sleep problems have long been associated with Alzheimer's disease and other forms of dementia. "Many older adults have problems sleeping, but people with dementia often have an even harder time," explain Mayo Clinic experts. In fact, they explain that sleep disturbances affect up to 25 percent of patients with mild to moderate dementia, and half of patients with severe dementia. These sleep disturbances tend to get worse as dementia progresses in severity, they note.

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Doing this at night may spike your dementia risk.

Older couple sleeping in bed

According to a 2022 study published in the Journal of the American Geriatrics Society, sleep and dementia are linked in several ways. The researchers behind the study say that certain sleep characteristics may help reveal your dementia risk, even if you're currently in good cognitive health.

To explore the link between sleep characteristics and dementia, the team collected questionnaire data from 1,982 participants in rural China, all of whom were 60 years or younger and dementia-free at the start of the study. Over the course of the following four years, 97 of those individuals developed dementia.

After analyzing the sleep data of those who developed cognitive decline and comparing it to those who did not, the team learned that senior men who spent more than eight hours in bed per night were at 69 percent greater risk of dementia than those who were in bed for between seven and eight hours. The risk was also twice as high for those who went to bed before nine o'clock in the evening, compared to those who went to bed at 10 p.m. or later.

The study didn't establish causality, but here's how these factors may be linked.

woman lying on bed at home unhappy and sleepless at night feeling overwhelmed suffering depression problem and insomnia

The study authors write that there may be multiple reasons that a longer time spent in bed or a consistently earlier bed time could contribute to a higher likelihood of dementia. "Several potential mechanisms may explain the associations of sleep problems with dementia and cognitive decline. Long sleep duration has been associated with global brain atrophy, more white matter hyperintensities, and proinflammatory biomarkers… which may be the pathways linking long sleep duration to dementia," they theorize.

However, it's important to note that the study did not establish causality, and the researchers admit that the exact reasons for the associations "are unknown." It's possible that interrupted or poorer quality nighttime sleep—long associated with dementia—causes daytime sleepiness and earlier bedtimes, as well as longer total time spent in bed.

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Too little sleep is also linked with increased dementia risk.

Sleep Apnea Oxygen Mask Equipment And CPAP Machine

Sleep is essential for healthy cognitive function, and getting too little of it has also been shown to increase your likelihood of developing dementia. Studies suggest that getting a minimum of seven hours of quality sleep per night helps to stave off cognitive decline.

However, people who get six hours of sleep or less are at significantly heightened risk of dementia and other illnesses—and those getting under five hours per night may be in outright danger. A 2020 study conducted by researchers at Harvard Medical School examined sleep data from 2,800 individuals aged 65 and older and found that those who slept less than five hours per night were twice as likely to develop dementia within five years. They also observed that those individuals were twice as likely to die of any cause within that five year period, compared to those who slept six to eight hours per night.

Taken together, these studies all seem to have a common message, despite their seemingly polarized findings: that both quantity and quality of sleep matter greatly when it comes to your cognitive and general health. Speak with your doctor for more information if you believe your sleep is negatively affecting your wellbeing.

Lauren Gray
Lauren Gray is a New York-based writer, editor, and consultant. Read more
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