The research team investigated how different combinations of sleep habits and physical activity could affect people’s cognitive function over time.
Regular physical activity may protect against cognitive decline as we age, but this protective effect may be diminished for people who do not get enough sleep, according to a new study by UCL researchers.
The study, published in The Lancet Healthy Longevity , looked at cognitive function over 10 years in 8,958 people over the age of 50 in England. The research team investigated how different combinations of sleep habits and physical activity could affect people’s cognitive function over time.
They found that people who were more physically active but slept little (less than six hours on average) had more rapid cognitive decline overall, meaning that after 10 years their cognitive function was equivalent to that of their peers who did less physical activity.
Lead author Dr Mikaela Bloomberg (UCL Institute of Epidemiology and Healthcare) said: "Our study suggests that getting enough sleep may be necessary for us to reap the full cognitive benefits of physical activity. It shows what important to consider sleep and physical activity. activity together when thinking about cognitive health.
"Previous studies examining how sleep and physical activity might combine to affect cognitive function have been primarily cross-sectional, only focused on a snapshot in time, and we were surprised that regular physical activity is not always enough to counteract the effect." long time". long-term effects of sleep deprivation on cognitive health.
The study found, in line with previous research, that sleeping between six and eight hours a night and higher levels of physical activity were linked to better cognitive function.
Those who were more physically active also had better cognitive function, regardless of how long they slept at the beginning of the study. This changed over the 10-year period, with more physically active people who are short sleepers (less than six hours) experiencing more rapid cognitive decline.
This rapid decline was true for those ages 50 to 60 in this group, but for older participants (aged 70 and older) the cognitive benefits of exercise seemed to hold up, despite little sleep.
Co-author Professor Andrew Steptoe (UCL Institute of Epidemiology and Healthcare) said: "It is important to identify factors that may protect cognitive function in mid- and later life, as they may serve to cognitively prolong our years." healthy and, for some people, delay a dementia diagnosis.
"The World Health Organization already identifies physical activity as a way to maintain cognitive function, but interventions must also consider sleep habits to maximize long-term benefits for cognitive health."
For the study, the researchers used data from the English Longitudinal Study of Aging (ELSA), a nationally representative cohort study of the English population. Participants were asked how long they slept on an average weekday night and were divided into three sleep groups: short (less than six hours), optimal (six to eight hours), and long (more than eight hours).
They were also given a score based on the frequency and intensity of self-reported physical activity and were divided into two groups: more physically active (the top third of scorers) and less physically active (the other two-thirds). Cognitive function was assessed on the basis of an episodic memory test (asking participants to remember a list of 10 words, both immediately and after a delay) and a verbal fluency test (asking participants to name as many animals as they could in a minute).
The researchers adjusted for a number of confounding factors, such as whether participants had taken the same cognitive test before and were therefore likely to perform better. They also excluded people with self-reported dementia diagnoses and those whose test scores indicated any cognitive impairment, so that behavioral changes linked to preclinical Alzheimer’s disease (such as sleep disorders) did not inadvertently affect the results.
As for the limitations of the study, the researchers relied on participants to self-report sleep duration and physical activity. Next steps, the researchers said, may be to repeat the results in more diverse study populations, examine more cognitive domains and more sleep quality domains, and use objective measures such as a wearable physical activity tracker.
Interpretation The initial cognitive benefit associated with more frequent and higher intensity physical activity was insufficient to improve the more rapid cognitive decline associated with short sleep. Physical activity interventions should also consider sleep habits to maximize the benefits of physical activity for long-term cognitive health. |
The research was funded by the UK Economic and Social Research Council.
