18 Mar Excessive Daytime Naps May Be a Sign of Early Cognitive Decline
MedicalResearch.com Interview with:
Peng Li, Ph.D.
Assistant Professor of Medicine, Harvard Medical School
Research Director, Medical Biodynamics Program (MBP)
Division of Sleep and Circadian Disorders
Associate Physiologist, Brigham and Women’s Hospital
MedicalResearch.com: What is the background for this study?
Response: People commonly see increased sleep during daytime in older adults. In people with Alzheimer’s disease or dementia, daytime drowsiness or sleepiness are even more common. Prior studies have showed protective effects of short naps on cognitive performance and alertness acutely, while also there are studies that have demonstrated more daytime naps are associated with faster cognitive decline in the long-term. We sought to investigate whether daytime napping behavior predicts future development of Alzheimer’s dementia. And we noted that there had been no studies to date that have documented the longitudinal profile of daytime napping during late life objectively.
MedicalResearch.com: What are the main findings?
Response: Based on objectively assessed napping behaviors during daytime using actigraphy, we found that older adults tended to nap longer and more frequently as they grew even older, and these changes sped up dramatically with the progression of Alzheimer’s dementia. We also found that longer and more frequent daytime naps in cognitively normal adults predicted an elevated risk of developing Alzheimer’s dementia in the future. By modeling daytime napping behavior and cognition simultaneously, we found that the two processes drove each other’s changes bi-directionally, so that longer/more frequent daytime naps were associated with worse cognitive performance in the following year, and worse cognitive performance predicted even longer/more frequent daytime naps in the subsequent year.
MedicalResearch.com: What should readers take away from your report? Should patients try not to nap during the day?
Response: The take-home message is that excessive daytime naps may be a sign of future negative cognitive outcomes such as Alzheimer’s dementia. However, we should be cautious to draw a causal relationship—we don’t know whether it is the chicken, egg, or both. It is possible that changes in daytime napping behavior may lead to or be a result of disruptions in nighttime sleep or our circadian clocks, as occurs in shift workers — both are known to link with Alzheimer’s disease. Excessive naps may also be a sign of other underlying pathophysiological changes that cause cognitive decline and dementia.
Our study, nevertheless, calls for a closer attention of sleep health, not only the typical referred sleep during nighttime, but also daytime naps. Besides, people should pay attention to changes in their sleep behavior since our study also showed that a faster increase in nap duration or frequency may also mean an unfavorable change in cognition. We would not recommend patients or older adults try to avoid napping during the day, instead, we would recommend they maintain a regular daily behavior pattern, including nap and sleep, and seek further medical advice if they or their close family members recognize drastic changes in the sleep behaviors.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: Future studies should investigate whether a direct intervention on daytime sleep behavior can help prevent negative cognitive outcomes. Besides, future research should also study a younger population, or investigate whether earlier life sleep patterns, 24-hour sleep patterns, are related to late life cognitive impairment or dementia. What’s also worth further investigations is whether our observed associations differ by culture, since nap or siesta is a common thing in some cultures such as in Spain and China, etc.
MedicalResearch.com: Is there anything else you would like to add?
Response: We would like to mention that although we used actigraphy to assess daytime sleep patterns, the gold standard for sleep assessment is polysomnography, which should be used for better understanding of the sleep architecture during daytime and its link with Alzheimer’s. The study also calls for technical advances to increase the accuracy of actigraphy-based sleep scoring in order to promote the use of actigraphy in long term monitoring of sleep patterns, especially in older adults.
Nothing to disclose.
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