When you get a bad night of sleep, it’s common the next day to feel like your brain isn’t operating at 100 percent. But a new study suggests that regularly having trouble falling or staying asleep could lead to even bigger issues, with long-term consequences for brain health.
The study, published in Neurology, suggests that people who have chronic insomnia — meaning they experience trouble sleeping three days a week or more for at least three months — may be at an increased risk for cognitive impairment and dementia.
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For the study, researchers examined data on 2,750 cognitively healthy older adults, average age about 70, over a period of roughly five years. Around 16 percent had chronic insomnia.
All participants underwent yearly cognitive testing, including brain imaging in some cases, to analyze the potential link between brain changes and the sleep disorder.
By the end of the study period, 14 percent of participants with chronic insomnia developed mild cognitive impairment or dementia, compared with 10 percent of people who didn’t have insomnia.
After adjusting for factors like age, use of sleep medications, and diagnosis of another sleep disorder like sleep apnea, the researchers determined that people with insomnia were 40 percent more likely to develop mild cognitive impairment or dementia — which the research team equates to an additional 3.5 years of brain aging.
“[Our results suggest that] insomnia may be a modifiable risk factor for poorer brain health and dementia. Therefore, those individuals struggling to fall or stay asleep should pursue medical evaluation to help mitigate the risk,” says lead study author Diego Carvalho, MD, an assistant professor of neurology and a sleep medicine physician at the Mayo Clinic Center for Sleep Medicine in Rochester, Minnesota.
How Poor Sleep May Impact Brain Health
Research has shown that sleep is key for a variety of brain functions, including cognitive health, which is the ability to think, learn, and recall. Some studies suggest that sleeping helps clear built-up toxins from the brain that could contribute to the development of age-related conditions like Alzheimer’s disease.
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Dr. Carvalho says the new investigation adds to the growing body of evidence indicating a connection between poor sleep and cognitive decline. “However, few studies have looked specifically into insomnia diagnosis and the brain changes we evaluated for,” he says.
At the start of the study, researchers also asked the participants with insomnia whether they’d been sleeping more or less than usual during the past two weeks.
Then, using brain scans, the research team looked for changes associated with cognitive issues: pockets of tissue damage known as white matter hyperintensities and protein deposits called amyloid plaques.
Participants with insomnia who reported sleeping less than usual in those two weeks had more white matter hyperintensities and amyloid plaques than participants with insomnia who noted no such issues. They were also more likely to score lower on cognitive tests.
On the other hand, participants with insomnia who reported getting more sleep than usual in the two weeks prior to the beginning of the study were more likely to have fewer white matter hyperintensities, which could signal less cognitive risk.
Study Shares Valuable Insights but Has Limitations
“These findings underscore that sleep is vital for brain health. When we see that insomnia can damage brain structures and accelerate cognitive decline, it becomes clear that treating sleep disorders must be a fundamental pillar of healthcare,” says Jennifer Martin, PhD, spokesperson for the American Academy of Sleep Medicine and a professor of medicine at the David Geffen School of Medicine at UCLA in Los Angeles, who was not involved in the study.
The study authors note that the research did not evaluate for insomnia severity or changes in insomnia symptoms over time. In addition, sleep habits — including the perception of how much sleep a participant was getting — were self-reported, without objective sleep study data to analyze sleep duration and other sleep characteristics, Carvalho says.
Dr. Martin also points out the participant pool may limit the ability to generalize the findings to all people. “Over 90 percent of the study participants were white, even though sleep disorders impact people of all races and ethnicities,” she says.
What Counts as Insomnia?
As the most common sleep disorder, insomnia
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can affect anyone, though it’s particularly prevalent in certain populations like older adults — with as many as three out of four adults age 65 and older experiencing insomnia symptoms.
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People with insomnia have trouble falling and staying asleep, wake up several times per night, and may not feel refreshed in the morning — even when timing and other sleep hygiene factors are ideal. This leads to daytime grogginess, which can interfere with daily routine and life.
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Roughly 1 in 10 adults in the United States report being diagnosed with chronic insomnia.
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This type of insomnia is often the side effect of a medical condition, medication, substance use, or other sleep disorder — and it’s different than being a night owl, or having what experts classify as an evening-type chronotype, which refers to the body’s natural sleep-wake pattern.
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“The main difference is that people who are night owls sleep well if they can choose their own schedule, like going to bed late and sleeping in,” says Martin. “People with insomnia can’t sleep well no matter when they try to. Being a night owl is not necessarily a problem if you can adjust your schedule and get the sleep you need.”
Insomnia Is ‘Very Treatable’
“Studies like this underscore the potentially serious long-term consequences of sleep deprivation, a growing concern as our population ages. Most importantly, this study identifies the opportunity to target sleep health improvement as a protective factor against cognitive decline,” says Martin.
Martin says insomnia is “very treatable,” once diagnosed by a physician or other healthcare professional. Treatment options can include:
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“While we all experience sleepless nights here and there, if insomnia occurs several times a week for at least a month, impacts daily activities or mood, or does not improve with self-care efforts, you should consider seeing a doctor,” says Martin.
