Drowsy during the daytime?

For seniors, such sleepiness could indicate that they’re at increased risk for dementia, a new study suggests.

Women in their 80s had double risk of dementia if they experienced increasing daytime sleepiness over a five-year period, researchers reported in the journal Neurology.

“Sleep is essential for cognitive health, as it allows the brain to rest and rejuvenate, enhancing our ability to think clearly and remember information,” senior researcher Yue Leng, an associate professor of psychiatry at the University of California-San Francisco, said in a news release.

“Our study found that sleep problems may be intertwined with cognitive aging and may serve as an early marker or risk factor for dementia in women in their 80s,” Leng added.

For the study, researchers tracked 733 women with an average age of 83 for five years. None had mild cognitive impairment or dementia at the start.

The women wore wrist devices to track their sleep for three days at the start and the end of the study.

The devices showed that about 56% had experienced large changes in their sleeping patterns during the intervening five years.

Over the study's five years, 22% developed mild cognitive impairment and 13% dementia.

Changing sleep patterns appeared to be linked to risk for declining brain function, results show.

Only 8% of women whose sleep patterns didn’t change developed dementia, compared with 15% of those whose nighttime sleep had become worse and 19% of those who were sleepier during the day.

Women with increasing sleepiness had 2.2 times the risk of dementia, after adjusting for other risk factors, researchers concluded.

“We observed that sleeping, napping and circadian rhythms can change dramatically over only five years for women in their 80s,” Leng said.

“This highlights the need for future studies to look at all aspects of daily sleep patterns to better understand how changes in these patterns over time can be linked to dementia risk," she added.

These results indicate that sleep might be a key factor in protecting brain health, says an accompanying editorial co-written by Dr. Marino Muxfeldt Bianchin, a professor of internal medicine with the Federal University of Rio Grande do Sul in Brazil.

“Initiatives focusing on improving sleep efficiency, encouraging lifestyle changes, and implementing cognitive interventions may be essential in mitigating dementia risk in the aging population,” Bianchin wrote.