Regular physical activity and getting the recommended amount of sleep may reduce dementia risk later in life, according to a new study by Akinkunle Oye-Somefun and colleagues of York University, Canada, published April 8, 2026 in the open-access journal PLOS One.
An estimated 55 million people live with dementia worldwide, and both its prevalence and cost are expected to increase, with global costs projected to reach $2 trillion dollars by 2030. Current treatments for preventing or treating dementia have limited efficacy; therefore, public health efforts have also aimed at healthy lifestyle factors to reduce the risk of dementia before symptoms occur. Healthy behaviors such as regular physical activity and good sleep hygiene are known to support cognitive health; however, there remains a need to better understand their relationship to dementia.
In this systematic review and meta-analysis, researchers analyzed data from 69 prospective cohort studies representing millions of community-dwelling adults aged 35+, to see if there was a link between the development of dementia and three lifestyle behaviors: physical activity, sedentary behavior, and sleep duration. Each of the observational studies recorded behaviors of cognitively healthy participants, then followed up at a later timepoint to report subsequent rates of dementia.
Overall, the meta-analysis found that regular physical activity, less sedentary time, and appropriate nightly sleep (7–8 h) were associated with a lower subsequent risk of dementia. Regular physical activity was associated with an average 25% lower risk of dementia among the 49 studies analyzed; however, the researchers note that there was considerable heterogeneity between the studies.
Too little sleep (<7 h) or too much sleep (>8 h) was associated with an 18% and 28% higher subsequent risk of dementia, respectively, compared to optimal nightly sleep of 7-8 hours, though there was again considerable heterogeneity among the 17 studies analyzed. Prolonged sitting (>8 hours per day) was associated with a 27% higher risk of dementia among the 3 relevant studies analyzed.
The study is consistent with and expands on previous research, using a large, diverse population with long follow-up times. While the study design cannot show any causative link between physical activity, sleep and dementia, the findings suggest an association between adherence to recommended physical activity and sleep levels in middle- and older-age adults and lowered dementia risk later in life.
The authors add: "Dementia develops over decades, and our findings suggest that everyday behaviours such as physical activity, time spent sitting, and sleep duration may be linked to dementia risk. Understanding how each of these behaviours relates to risk over time may help researchers identify opportunities to support brain health across the life course."
"Separately, one aspect I personally found most interesting while conducting the study was the relatively limited evidence base on sedentary behaviour. Despite growing recognition that prolonged sitting is distinct from physical inactivity, we found only a small number of cohort studies examining its relationship with dementia risk. This highlights an important gap for future research."
In your coverage, please use this URL to provide access to the freely available article in PLOS One: https://plos.io/4ddHCAa
Citation: Oye-Somefun A, Mirzadeh P, Gao-Kang J, Rotondi M, Kuk JL, Tamim H, et al. (2026) The Relationships between physical activity, sedentary behaviour, sleep, and dementia: A systematic review and meta-analysis of cohort studies. PLoS One 21(4): e0343621. https://doi.org/10.1371/journal.pone.0343621
Author countries: Canada
Funding: The author(s) received no specific funding for this work.
