Dementia risk nearly doubles among those with common sleep disorder, study finds
Chronic insomnia linked to higher dementia risk and signs of accelerated brain aging, study shows; researchers urge attention to sleep health.
A new large study published in Neurology found that chronic insomnia is associated with a markedly higher risk of cognitive impairment and dementia in older adults. The research followed 2,750 cognitively healthy adults with an average age around 70 for more than five and a half years, and identified a clear link between persistent sleep problems and later brain health outcomes. About 16 percent of participants reported chronic insomnia during the study period, defined as difficulty falling asleep or staying asleep for a prolonged time.
In the main finding, participants with chronic insomnia were about 40 percent more likely to develop cognitive impairment or dementia than those without the sleep disorder. After follow-up, 14 percent of the insomnia group developed mild cognitive impairment or dementia, compared with 10 percent of those without chronic insomnia. The risk increase persisted after controlling for age, high blood pressure, sleep apnea diagnoses, and use of sleep medications.
Researchers also found that among those with chronic insomnia, some brain changes related to small vessel disease appeared to plateau or even lessen when individuals reported sleeping longer than usual. MRI findings showed fewer white matter spots, which are linked to vascular brain injury, in this subgroup. Additional cognitive testing revealed lower scores in thinking and processing speed among insomnia sufferers, even after adjusting for other factors. The authors caution that this does not prove causation, but it suggests a relationship between sleep duration, brain structure, and cognitive health.
Lead author Diego Z. Carvalho, M.D., of the Mayo Clinic in Rochester, Minnesota, said that chronic insomnia was defined as persistent difficulty falling or staying asleep, distinguishing it from the broader quest for perfect sleep. He emphasized that even a relatively short period of chronic insomnia could have lingering cognitive effects later in life and that sleep health may be a modifiable risk factor for dementia.
Chronic insomnia appeared more harmful among carriers of the APOE ε4 gene, which is linked to higher Alzheimer's risk, who showed larger declines in memory and executive function. The study’s authors suggested that sleep health interventions could potentially slow cognitive decline for at risk individuals.
The researchers noted several limitations. They did not have longitudinal objective sleep data beginning at baseline to quantify sleep duration precisely over time, and they could not fully account for how many participants used obstructive sleep apnea treatment, such as CPAP, or the dosage and duration of sleep medications. The findings represent associations, not proof that insomnia directly causes brain aging.
The study’s implications extend beyond academic interest. Experts say addressing chronic insomnia could be a straightforward path to protecting brain health in aging populations. Interventions such as cognitive behavioral therapy for insomnia, along with sleep hygiene measures, were repeatedly recommended. Avoiding late-day caffeine, reducing alcohol intake, not eating large meals right before bed, and limiting electronic device exposure at night are among the practices clinicians advocate.
Some researchers cautioned that while the brains glymphatic system and waste clearance are active during sleep, the precise mechanisms linking insomnia to neurodegeneration remain to be fully understood, and long-term trials are needed to determine whether improving sleep translates into reduced dementia risk. Dr. Marc Siegel, senior medical analyst for Fox News, said the study shows an important association between sleep deprivation and cognitive decline, but emphasized that causation is not established by this work.
Neurology is the journal of the American Academy of Neurology, and the study was supported by the NIH, GHR Foundation, Mayo Clinic, and a grant from Sleep Number Corporation. The study authors urged clinicians to address insomnia as a potential modifiable risk factor in aging and to promote sleep health as part of overall brain health.
The research team emphasized that improving sleep practices may reduce health risk over time, but they cautioned that strong conclusions about causation require further study. Melissa Rudy, senior health editor at Fox News Digital, noted that ongoing research will help clarify how sleep affects brain aging and dementia risk.