A new study published Thursday in Alzheimer’s and Dementia: The Journal of the Alzheimer’s Association has revealed that excessive napping for extended periods during the day is associated with early dementia in older adults, according to CNN.

The study found that older people who napped at least once a day or more than an hour a day were 40% more likely to develop Alzheimer’s disease.

The study’s co-senior author Dr. Yue Leng of the University of California, San Francisco, said, “We found the association between excessive daytime napping and dementia remained after adjusting for nighttime quantity and quality of sleep.”

The findings highlight the result of a previous study by Dr. Leng that found two-hour napping a day increases the risk of cognitive impairment.

Dr. Richard Isaacson of the Alzheimer’s Prevention Clinic in the Center for Brain Health at Florida Atlantic University’s Schmidt College of Medicine said, “I think the public isn’t aware that Alzheimer’s is a brain disease that oftentimes causes changes in mood and sleep behavior.”

“Excessive napping may be one of the many clues that a person could be on the road to cognitive decline, and trigger an in-person evaluation with a treating physician,” added Dr. Isaacson, who was not part of the study.

Dr. Leng said daytime napping could be a sign of brain changes that are “independent of nighttime sleep.” She said the development of tau tangles, a hallmark sign of Alzheimer’s, might be affecting wake-promoting neurons in key areas of the brain, thereby disrupting sleep.

Dr. Isaacson said, “Further studies are warranted with devices that are validated to detect sleep versus sedentary behavior. But at the same time, being sedentary and not moving for long periods of time Is a known risk factor for cognitive decline and Alzheimer’s.”

“Regardless of the reason, falling asleep during the day or excessive napping raises my antenna to focus on whether the person may be at higher risk for Alzheimer’s disease or cognitive decline,” he added.

Dr. Leng explained that the “drastic increase” in napping length and frequency over the years could be an important signal.

She said, “I don’t think we have enough evidence to draw conclusions about a causal relationship, that it’s the napping itself that caused cognitive aging, but excessive daytime napping might be a signal of accelerated aging or cognitive aging process.”

Considering the findings of the current study, older adults and caregivers of people with dementia should pay close attention to daytime napping behaviors. They should be alert to any signs of excessive napping. Dr. Isaacson said any significant increase in napping behavior must be discussed with a doctor.