Feeling sleepy during the day could signal a more serious issue for some groups.
A new study published in the journal Neurology revealed a possible connection between daytime sleepiness in older people and dementia risk.
People who lack enthusiasm for activities and feel sleepy during the day were found to have a higher risk of developing a condition called motoric cognitive risk syndrome (MCR).
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MCR can cause people to walk at slower speeds and experience memory issues – and it can occur before dementia develops.
The study, led by Albert Einstein College of Medicine in the Bronx, New York, included 445 participants averaging 76 years of age who did not have dementia.
Participants were asked about memory issues and walked on treadmills to assess their walking speeds. This was repeated once a year for an average of three years.
The group also completed a sleep assessment to gauge sleeping problems, patterns and medications.
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The researchers also tracked how often people had trouble staying awake while driving, eating or being social, as well as their issues maintaining enthusiasm for daily tasks.
At the start, 42 people had MCR, while another 36 developed the condition during the study.
After adjusting for factors like age, depression and other health conditions, researchers found that people with a lack of enthusiasm and daytime sleepiness were more than three times as likely to develop MCR.
"Our findings suggest that sleep issues affecting daytime wakefulness are most strongly associated with later cognitive risk," study author Victoire Leroy, MD, PhD, of Albert Einstein College of Medicine in New York, told Fox News Digital.
"This supports the hypothesis that sleep-related problems, particularly daytime sleepiness, are connected to cognitive impairment in older adults."
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"More research needs to be done to look at the relationship between sleep issues and cognitive decline and the role played by motoric cognitive risk syndrome," Leroy added.
The study did have some limitations, the researchers noted.
It did not prove that sleep-related issues cause MCR, but only showed an association. Participants also self-reported their own sleep information, which left some room for bias.
"These results should be interpreted with caution due to several limitations in the study, and the association is not shown to be causal," Leroy told Fox News Digital.
"Further research is needed to validate this relationship and its underlying mechanisms."
Sleep expert Dr. Wendy Troxel, RAND Corporation senior behavioral specialist and licensed clinical psychologist in Utah, commented on the study in a conversation with Fox News Digital.
As sleep problems and depression are "highly related," it’s "important to disentangle whether their sleep problems uniquely contribute to MCR, over and above the effects of depression," said Troxel, who was not involved in the study.
"Results showed that people with poor sleep quality had a higher chance of developing MCR, but this link was no longer significant when accounting for depression," she added.
Sleep-related daytime impairment remained a significant risk factor for MCR even after adjusting for depression, according to Troxel.
"These findings add to a growing body of evidence suggesting that promoting sleep health may be an important strategy to reduce the risk of dementia and emphasize the need for better screening and diagnosis for sleep disorders, such as insomnia and sleep apnea," she said.
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These disorders are "prevalent and treatable" in both men and women, Troxel noted, but they remain "under-diagnosed and under-treated."
The study was supported by the National Institute on Aging.