Investigators in a new study were surprised to find that people who reported having sleep-maintenance insomnia—trouble falling back to sleep after waking—had a lower likelihood of developing dementia over the course of the research.

The results, reported in the American Journal of Preventive Medicine, associate sleep-initiation insomnia (trouble falling asleep within 30 minutes) and sleep medication use with a higher risk of developing dementia, a finding investigators were unsurprised by. They were surprised, however, by the link between sleep-maintenance insomnia and a reduced risk of dementia. 

“We expected sleep-initiation insomnia and sleep medication usage to increase dementia risk, but we were surprised to find sleep-maintenance insomnia decreased dementia risk,” says lead investigator Roger Wong, PhD, an assistant professor in the Department of Public Health and Preventive Medicine at SUNY Upstate Medical University, in a press release. “The motivation behind this research was prompted on a personal level. My father has been experiencing chronic sleep disturbances since the COVID-19 pandemic began, and I was concerned how this would affect his cognition in the future. After reading the existing literature, I was surprised to see mixed findings on the sleep-dementia relationship, so I decided to investigate this topic.”

This research is novel because it is the first to examine how long-term sleep disturbance measures are associated with dementia risk using a nationally representative US older adult sample, according to a press release by Elsevier, which published the study. Previous research has associated REM sleep behavior, sleep deprivation, and the use of short-acting benzodiazepines with cognitive decline. Their results for sleep-maintenance insomnia support other recent studies using smaller, separate data samples.

This study used 10 annual waves (2011−2020) of prospective data from the National Health and Aging Trends Study, a longitudinal panel study that surveys a nationally representative sample of Medicare beneficiaries aged 65 years and older within the US. This study included only people who were dementia-free at baseline in 2011.

There is no cure for dementia, and recent pharmaceutical approaches to treat dementia have had limited success, pointing to the importance of preventive approaches to dementia. 

“By focusing on the variations in sleep disturbances, our findings can help to inform lifestyle changes that can reduce dementia risk,” says co-investigator Margaret Anne Lovier, Department of Public Health and Preventive Medicine at SUNY Upstate Medical University, in a press release.

While the mechanism for decreased dementia risk among those with sleep-maintenance insomnia is still unknown, the investigators theorize that greater engagement in activities that preserve or increase cognitive reserve may thereby decrease dementia risk.

Recent evidence indicates there is a higher prevalence of sleep disturbances among older adults than among other age groups. 

“Older adults are losing sleep over a wide variety of concerns. More research is needed to better understand its causes and manifestations and limit the long-term consequences,” says Wong in the press release. “Our findings highlight the importance of considering sleep disturbance history when assessing the dementia risk profile for older adults.”

Future research is needed to examine other sleep disturbance measures using a national longitudinal sample, whether these sleep-dementia findings hold true for specific dementia subtypes, and how certain sociodemographic characteristics may interact with sleep disturbances to influence dementia risk, according to Wong. 

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