Daytime nappers display poorer cognitive abilities

The association between sleep and cognition in older adults
Cognitive impairment and sleep disorders are common determinants of older adult health. However, earlier studies found mixed and inconsistent results on the association between the type of sleep disturbance, e.g., short nighttime sleep or waking up early, and the cognitive impairment affected, e.g., memory or executive functioning. This study examined cross-sectional and longitudinal associations between several self-reported sleep disturbances and cognitive domains.

Four NEAR population studies: the Gothenburg H70 Birth Cohort Study (H70); Kungsholmen Project (KP), Swedish National Study on Aging and Care in Skåne (SNAC-S), and Kungsholmen (SNAC-K), were used to explore this, as well as the Finnish study Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study.

Photo: Josefine Anjou

Excessive daytime napping was associated with poorer cognitive abilities
In 5631 persons aged 71-84 years (mean age 78 years), excessive daytime napping (>2 hours) was associated with impaired cognitive abilities such as episodic memory, verbal fluency, perceptual speed, and executive functioning. The study also showed that insomnia symptoms (i.e., sleep latency, waking up at night, and early awakenings) were related to poor episodic memory. Participants sleeping for shorter or longer than 7-8 hours per night had a steeper decline in perceptual speed, compared to those sleeping 7-8 hours per night. Except for daytime napping, most associations were study-specific, and most remained significant after adjusting for various demographic and lifestyle factors, as well as cardiovascular conditions. Overall, targeting specific sleep behaviors, such as insomnia and daytime napping in future lifestyle interventions for older adults can counteract cognitive decline.

Marieclaire Overton, first author of the study. Photo: Private

Congratulations Marieclaire on your results! What was it like working with NEAR data?
It was a very educational, inspiring, and great experience to get to know other researchers, databases, and aging studies.

Most unexpected research finding:
That exceptionally long daytime napping (more than 2 hours) was associated with worse performance on a range of cognitive abilities. This was surprising as previous studies suggested that daytime napping in older adults is beneficial for mental health, but it seems that it has to do with the duration of the naps, shorter naps are better for cognitive functioning whereas longer may be disadvantageous.

Best tips for working with NEAR data:
To get to know the data before analyzing, this can be done by contacting researchers connected to the respective aging studies. Ask about the best ways to categorize variables or patterns in the data/sample that only researchers of the specific study understand/know.

Best tips for unwinding before bedtime:
I have heard that a hot shower is great, as it helps lower core temperature, but my favorite is a good audiobook – it never fails to make me sleepy!

Best tips to regain focus:
Have a break and take a walk. I usually process a lot during a walk, which I am eager to put in print when I get back to the desk.

Publication
Overton MC,  Skoog J, Laukka EJ, Hadarsson Bodin T, Darin Mattsson A, Sjöberg L, Hofer SM, Johansson L, Kulmala J, Kivipelto M, Solomon A, Skoog I, Kåreholt I, Sindi S. Sleep disturbances and change in multiple cognitive domains among older adults: A multicentre study of five Nordic cohorts. Sleep. 2023; Sep 14:zsad244. Online ahead of print. doi.org/10.1093/sleep/zsad244.