Frequent and Longer Daytime Naps Indicate Heightened Risk of Alzheimer’s Disease

A new study reveals that frequent and longer daytime naps may be an indicator of an older adult’s risk of Alzheimer’s disease and that those afflicted with a worsening case of Alzheimer’s tend to sleep longer and more frequently in the daytime.

“Daytime sleep behaviors of older adults are oftentimes ignored, and a consensus for daytime napping in clinical practice and health care is still lacking. Our results not only suggest that excessive daytime napping may signal an elevated risk of Alzheimer’s dementia, but they also show that faster yearly increase in daytime napping may be a sign of deteriorating or unfavored clinical progression of the disease,” said Peng Li of the Medical Biodynamics Program in the Brigham’s Division of Sleep and Circadian Disorders.

There have been studies on this matter in the past but always with conflicting results. But the authors of this latest study deviated from the methodology of all the past studies, which were largely questionnaire-based and obtained from a single assessment of a participant.

In this cohort study of 1401 participants with an average age of 81 years, each of them was provided with an Actical, which is a watch-like device that they wore on their non-dominant wrists for up to two weeks.

Sleep episodes were identified using a previously validated sleep scoring algorithm that takes into consideration wrist activity counts. Afterward, the nap frequency and duration were calculated. The results made the authors discover a “vicious cycle” between Alzheimer’s and daytime naps.

“The vicious cycle we observed between daytime sleep and Alzheimer’s disease offers a basis for better understanding the role of sleep in the development and progression of Alzheimer’s disease in older adults,” said Li.

The study results made clear that daytime sleeping and Alzheimer’s are correlated longitudinally. Those normal older adults who take longer and frequent day naps have a higher risk of developing this form of dementia. On the other hand, those people with a fast-deteriorating case of Alzheimer’s tend to take longer and more frequent daytime naps.

“Our hope is to draw more attention to daytime sleep patterns and the importance of patients noting if their sleep schedule is changing over time,” added co-senior author Kun Hu of the Medical Biodynamics Program in the Brigham’s Division of Sleep and Circadian Disorders. “Sleep changes are critical in shaping the internal changes in the brain related to the circadian clocks, cognitive decline and the risk of dementia.”

The study was carried out in collaboration with the Rush Alzheimer’s Disease Center and the University of California, San Francisco.