- The researchers looked at cognitive function over 10 years in 8,958 people aged 50 and over in England.
- The study found that people who slept between 6 and 8 hours a night and engaged in higher levels of physical activity were linked to better cognitive function.
- People who slept less than 6 hours a night, even when engaging in higher levels of physical activity, experienced faster cognitive decline over ten years.
- Among participants aged 70 and older, the benefits of higher levels of physical activity on cognitive function appeared to be maintained despite the number of hours of sleep.
Evidence from existing research suggests that physical activities are beneficial to brain health and may protect against the development of neurodegenerative conditions such as dementia and Parkinson’s disease. However, a new study has found that sleep deprivation may reduce those benefits gained from exercise.
Nearly 10 percent of adults age 65 and older in the United States have dementia and another 22 percent have mild cognitive impairment, according to a 2022 National Representative
Numerous studies have found that exercise can reduce the risk of developing dementia. Still,
Physical activity and sleep are factors thought to contribute independently to cognitive function, but are also interrelated, where greater physical activity correlates with better sleep quality, and physical activity may also regulate circadian rhythms, Mikaela Bloomberg, Ph.D., a researcher at University College London Institute of Epidemiology and Health Care, explained to Medical News Today.
A team of researchers from UCL, including Bloomberg, have found little existing research examining the impact of physical activity AND sleep on cognitive function. The studies they found were small and
Because sleep disturbances can be an early symptom of neurocognitive disorders such as dementia that cause cognitive dysfunction, it’s difficult to determine whether the findings we see in those previous studies are due to sleep’s effects on cognitive function or vice versa, Dr. Bloomberg said. . With this in mind, we wanted to examine how combinations of physical activity and sleep habits affected cognitive function over a long period of time.
An article by the UCL researchers on their large-scale longitudinal study appears
For their study, the UCL researchers used longitudinal data on 8,958 cognitively healthy adults from England aged 50 and over from the English Longitudinal Study of Aging (ELSA). The data used was collected between January 1, 2008 and July 31, 2019.
Participants provided reports on their physical activity and sleep duration every two years.
Researchers asked participants how many hours they slept on a typical night of the week. The UCL researchers then classified sleep as short if it lasted less than six hours, optimal if between six and eight hours, and long if more than eight hours were received.
The researchers also asked the participants how much they exercised. Participants reported how often they participated in light, moderate, and vigorous physical activity and whether they exercised more than once a week, weekly, one to three times a month, and rarely/never.
Researchers assessed participants’ episodic memory using the Consortium to Establish a Registry for Alzheimer’s disease immediate and delayed recall. Researchers gave participants a list of ten words and asked them to recall the words immediately and again the next day. The researchers also assessed the participants’ verbal fluency using a task in which participants named as many animals as they could think of over the course of a minute.
The UCL researchers excluded participants who reported being diagnosed with dementia during the follow-up period, as well as participants whose test scores suggested cognitive impairment. Additionally, the researchers adjusted their analyzes for a number of factors, such as whether participants had taken the same cognitive test previously.
Of the 3,069 participants the researchers placed in the highest physical activity category, 1,525 participants (50%) reported engaging in light, moderate, and vigorous exercise more than once a week. Another 1,161 participants (37.8%) reported engaging in light to moderate exercise more than weekly and vigorous exercise monthly or weekly.
Among the 5,889 participants in the lowest physical activity category, 2,384 participants (40.5%) reported doing no vigorous physical activity at all but more than one weekly light and moderate physical activity. An additional 1,511 participants (25.7%) reported doing light physical activity more than once a week, moderate physical activity weekly or less often, and no vigorous physical activity.
Participants who engaged in higher physical activity were more likely to sleep 68 hours a night. They were also more likely to be younger at baseline, male, married or had a partner, and had more education and wealth than those in the lowest physical activity group. Those in the highest physical activity group were more likely to never smoke, had lower body mass indexes (BMIs), fewer diagnoses of all chronic conditions, and fewer depressive symptoms than those in the lowest physical activity group.
Participants in the highest physical activity group generally had the highest baseline cognition scores regardless of how long they slept.
[H]However, for ages 50 and 60, those with higher physical activity and short sleep declined more rapidly such that after 10 years of follow-up, they had similar cognition scores as the lower physical activity groups, they write. the UCL researchers in their paper on the study.
We were surprised to see that the cognitive benefits associated with physical activity were reduced when participants had insufficient sleep duration, but these findings certainly line up with previous research indicating an important role of sleep in cognitive and physical recovery.
Doctor Bloomberg
Among the older participants (ages 70 and older) the cognitive benefits of exercise appeared to be maintained even among the poor sleepers.
Dr. Vernon Williams, a sports neurologist, pain management specialist and founding director of the Center for Sports Neurology and Pain Medicine at Cedars-Sinai Kerlan-Jobe Institute in Los Angeles, told MNT he appreciated seeing data on the The Importance of Long-Term Sleep – Long-term benefits in cognitive function.
The notion that both exercise and sleep are critical factors in maintaining cognitive health, coupled with evidence that maintaining physical health in the absence of optimal sleep health reduces the cognitive benefits of physical activity is compelling, said Dr. Williams.
Ryan Glatt, senior brain health coach and director of the FitBrain program at the Pacific Neuroscience Institute in Santa Monica, California, said MNT extension he found the study very interesting but noted limitations.
[T]here are potential issues with the accuracy of self-reported physical activity and sleep duration, and the potential presence of sleep disturbances or the effects of certain medications weren’t considered, Glatt said.
Dr. Bloomberg believes there may be a way to conduct this research that doesn’t rely on the truthfulness of the participants.
An interesting next step would be to use objective measurements of sleep and physical activity, for example, using wrist-worn accelerometers to see if we see similar results, he said MNT extension.
In the future, the UCL researchers would also like to see a similar study performed in more diverse populations. Also, Dr. Bloomberg said MNT extension would like to extend the findings to dementia.
We purposely excluded those with dementia and those with cognitive scores that suggested cognitive impairment, in order to make it more likely we were capturing the effects of sleep on cognitive function and not the other way around, Dr. Bloomberg said. Future research should [examine] how combinations of physical activity and sleep affect [the] risk of dementia.
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