Written by Corrie Pelc — Fact checked by Jill Seladi-Schulman, Ph.D.
Making healthy lifestyle choices, such as eating a healthy diet, not smoking, getting enough physical activity and proper sleep, can help lower a person’s risk for many medical conditions.
One such condition is dementia — a condition that negatively impacts a person’s thinking and memory skills.
“Dementia affects more than 55 million people worldwide, and despite decades of research, there is still no cure,” Akinkunle Oye-Somefun, PhD, from the School of Kinesiology and Health Science at York University in Canada, explained to Medical News Today.
“The treatments that exist can slow progression in some people, but they do not stop the disease. That is why identifying modifiable risk factors — behaviors people can change — remains a critical research priority. Behaviors like how much people move, how long they sit, and how long they sleep are among the most promising targets,” he explained.
Oye-Somefun is the first author of a new study published in the journal PLOS One that found getting both the recommended amount of physical activity and sleep may be key to helping reduce a person’s dementia risk.
Regular physical activity lowers dementia risk by 25%
For this study, researchers analyzed data from adult participants aged 35 and older from 69 previously conducted studies. Of these studies, 49 focused on participants’ physical activity, 17 on sleep duration, and three on sedentary behavior.
“These three behaviors are all part of the same daily routine,” Oye-Somefun explained. “They shape each other, and all three can be changed. There has been growing evidence linking each one to brain health, and I felt it was important to ask: what does the full picture look like when the best available evidence is pooled across millions of people? The answer is that all three are important, because it means there is more than one lever people can pull.”
At the study’s conclusion, researchers found that participating in regular physical activity was correlated with an average 25% lower risk of dementia.
“Physical activity is one of the most important drivers of brain health,” Oye-Somefun said.
“What makes this particularly meaningful from a public health standpoint is that the association held up across 49 studies. It also held up in middle-aged and older adults, which tells us that it is not too late, and the window for benefit is not closed by the time people are in their 50s or 60s and older.” — Akinkunle Oye-Somefun, PhD
Sitting 8+ hours a day increases dementia risk by 27%
When it came to sleep, scientists discovered that getting too little sleep — less than seven hours a night — was linked to an 18% higher risk of developing dementia. And sleeping too much — more than eight hours a night — increased dementia risk by 28%.
“This finding matters because both short and long sleep durations were linked to higher risk,” Oye-Somefun said. “Consistently sleeping outside the seven-to-eight-hour range, in either direction, may carry long-term implications for brain health — implications that are easy to overlook because they accumulate silently over decades.”
Additionally, Oye-Somefun and his team found that study participants who sat for more than eight hours a day increased their dementia risk by 27%.
“Sitting for long stretches is its own risk factor, and many adults spend much of the day sitting — often without knowing it,” Oye-Somefun said.
Breaking up sitting time is important
“Sitting at a desk for eight hours is quite common, and our findings suggest that kind of long, unbroken sitting is associated with brain health on its own. It is not just about adding movement to the day — breaking up time spent sitting also matters. Prolonged sitting may carry its own risk, even for people who are otherwise active.” — Akinkunle Oye-Somefun, PhD
“I do want to be transparent that this finding is based on fewer studies than the physical activity evidence, so we need more research before calling it settled,” he added. “But the signal is consistent given what we already know about prolonged sitting and cardiovascular disease, and it would be surprising if the brain were somehow unaffected.”
Low-risk strategies for overall cognitive health
MNT spoke with Dung Trinh, MD, an internist for MemorialCare Medical Group and chief medical officer of the Healthy Brain Clinic in Irvine, CA, about this study, who commented its findings add meaningful support to something many clinicians already believe: that everyday habits like staying physically active, getting adequate sleep, and avoiding too much sedentary time may play an important role in brain health.
“What makes it especially notable is the very large amount of data it brings together, which strengthens confidence that these associations are real and relevant,” Trinh continued.
“That said, this is still observational research, so it does not prove that these behaviors directly prevent dementia, but it does reinforce that they are sensible, low-risk strategies that fit well with what we already recommend for overall cardiovascular and cognitive health.” — Dung Trinh, MD
Trinh said the next steps in this research should move beyond association and better understand causation by doing more long-term intervention studies that test whether changing these habits can truly reduce dementia risk over time.
“I would also like to see researchers use more objective tools, such as wearable devices, to measure physical activity, sitting time, and sleep more accurately, since much of the current evidence relies on self-report,” he detailed.
“Future research should examine how these behaviors work together, because in real life exercise, sleep, and sedentary time are interconnected, and understanding that interaction could help us give more precise, personalized prevention advice,” he added.
How can I realistically get enough physical activity and sleep?
For readers who want to incorporate such healthy lifestyle choices into their daily life in the hopes of possibly lowering their dementia risk, Sanjula Dhillon Singh, MD, PhD, MSc (Oxon), assistant professor at Harvard Medical School, and principal investigator in the Brain Care Labs at Massachusetts General Hospital, said the key is finding approaches that are realistic and can be maintained over time.
“The evidence suggests that consistent, moderate changes are likely more impactful than short-term, high-effort interventions,” Singh explained to MNT.
“It’s also important to recognize that these behaviors do not occur in a vacuum. People’s ability to exercise regularly, get adequate sleep, or reduce sedentary time is shaped by their environment, work schedules, caregiving responsibilities, neighborhood safety, and access to resources. Because of this, there is no single ‘right’ way to implement these changes — what matters most is identifying strategies that are realistic and sustainable within the context of someone’s daily life.” — Sanjula Dhillon Singh, MD, PhD
For physical activity, Singh said that may mean integrating movement into existing routines, such as walking during breaks, active commuting, or short, scheduled sessions during the week.
For sleep, prioritizing regularity — going to bed and waking at similar times —may be more achievable and impactful than focusing solely on duration.
And for sedentary behavior, she said that even small interruptions to prolonged sitting — standing, stretching, or brief walks — can meaningfully shift overall exposure.
“Tools like the Brain Care Score can help make this feel more approachable,” Singh said.
“It brings together a range of factors linked to brain health — such as movement, sleep, and social connection — in a way that allows individuals to reflect on what may be most relevant in their own lives. Rather than focusing on any single behavior, it emphasizes that brain health is shaped by multiple, interacting factors over time. This kind of flexible, individualized approach can support long-term changes in ways that are realistic and meaningful for different people,” she explained.
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