Recent research findings add to the growing body of evidence linking sleep disorders to cognitive impairment and show significant associations between three measures of sleep disorders and the risk of developing dementia within ten years. The findings, published in Elsevier’s American Journal of Preventive Medicine, link difficulty falling asleep (taking more than 30 minutes to fall asleep) and the use of sleep medications to a higher risk of developing dementia. The researchers also found that people who reported sleep maintenance problems (difficulty falling back asleep after waking up) were less likely to develop dementia during the study.

How Long-Term Sleep Problems are Linked to Dementia Risk

“We expected that difficulty falling asleep and taking sleeping pills would increase the risk of dementia, but we were surprised that difficulty staying asleep reduced the risk of dementia,” explained lead researcher Roger Wong, PhD, MPH, MSW, assistant professor in the Department of Public Health and Preventive Medicine at SUNY Upstate Medical University in Syracuse, NY, USA. “The motivation for this research was personal. My father has suffered from chronic sleep problems since the start of the COVID-19 pandemic, and I was concerned about how this would affect his cognitive abilities in the future. After reading the existing literature, I was surprised to find mixed results on the link between sleep and dementia and decided to investigate this topic.”

This study is the first to examine the association between long-term sleep disturbances and dementia risk in a nationally representative sample of older adults in the US. Previous research has linked REM sleep behavior, sleep deprivation (less than five hours of sleep), and the use of short-acting benzodiazepines to cognitive decline. Their findings on sleep disturbances caused by sleep disorders support other recent studies that have used smaller, separate data sets. This study used 10 annual survey waves (2011–2020) of prospective data from the National Health and Aging Trends Study (NHATS), a longitudinal panel study that surveys a nationally representative sample of Medicare beneficiaries aged 65 and older in the US. This study included only individuals who did not have dementia at the start of the study in 2011.

Dementia is incurable, and recent pharmaceutical approaches to treating dementia have had limited success, highlighting the importance of preventive approaches to dementia. “By focusing on differences in sleep disorders, our findings may help recommend lifestyle changes that can reduce the risk of dementia,” said co-researcher Margaret Anne Lovier, MPH, Department of Public Health and Preventive Medicine, SUNY Upstate Medical University, Syracuse, NY, USA. The mechanism for the reduced dementia risk in people with sleep disorders is still unknown, but the researchers suspect that greater involvement in activities that maintain or increase cognitive reserves may reduce the risk of dementia.

Exploring Additional Measures of Sleep Disorders

Recent findings suggest that sleep disorders are more common in older adults than in other age groups. This could be due to a variety of factors, including anxiety about the COVID-19 pandemic or warmer nights as a result of climate change. “Older adults suffer from sleep disorders due to a variety of concerns. Further research is needed to better understand the causes and manifestations and to limit the long-term consequences,” added Dr. Wong. These findings underscore the importance of considering a history of sleep disorders when assessing the risk of dementia in older adults. Future studies need to use a national longitudinal study to examine additional measures of sleep disorders and clarify whether these findings on the association between sleep disorders and dementia also apply to specific dementia subtypes and how certain sociodemographic characteristics may interact with sleep disorders and influence dementia risk.