There are various reasons for daytime napping, such as stress or a lack of sleep the night before. However, As people age, a tendency to nap during the daytime could be connected to the beginnings of dementia.
The data patterns not only relate to the need to take nap but also the number that are taken and the duration of the snooze. An increased frequency or an increased duration has a connection with what is medically referred to as ‘mild cognitive impairment’ (this is a precursor of dementia).
The reason for the connection is due to the function of the wake-promoting neurons in key areas of the brain. Here, excessive daytime napping independent of nighttime sleep quality could be tied to pre-dementia or dementia.
The research was led by scientists from the Department of Psychiatry and Behavioral Sciences, University of California. The findings are based on an assessment of 1,401 participants of the Rush Memory and Aging Project.
The study participants were examined over a period 14 years. Each person was given an activity tracker, which was worn on the wrist for 14 days per year. The data from the activity tracker (which could also assess sleep) was compared with the results of several neurological tests. Specifically, the researchers looked for neuronal and neurotransmitter loss in wake-promoting neurons associated with tau tangles (tau is a protein contained within the axons of the nerve cells).
At the beginning of the study, 75.7 percent of the participants were medically assessed as not being cognitively impaired. Of the remainder, 19.5 percent had mild cognitive impairment and 4.1 percent had Alzheimer’s disease.
After analysing the data, it was found that while older adults tend to nap longer and more frequently as they age, the progression of dementia appears to accelerate this change in correlation with nap duration and frequency.
This is to the extent that longer or more frequent daytime napping was correlated with worse cognition a year later. For example, 24 percent of those who did not have cognitive impairment at the commencement of the study developed Alzheimer’s six years later. These participants napped for more than an hour per day, and this represents a 40 percent higher risk of developing Alzhiemer’s when contrasted with those who napped for less than an hour per day.
It is not yet clear, however, whether it is the napping itself that causes cognitive aging or whether excessive daytime napping is itself a signal of the cognitive aging process. Further research will be required to probe these possibilities.
The research has been published in the journal Alzheimer’s and Dementia, with the study titled “Daytime napping and Alzheimer’s dementia: A potential bidirectional relationship.”
