New research from Canada has added to growing evidence that lifestyle habits such as sleep duration, physical activity and sedentary behaviour may play an important role in reducing the risk of dementia. The large-scale analysis, drawing on data from millions of adults across multiple studies, identified a pattern suggesting that both insufficient and excessive sleep may be associated with higher risk of neurodegenerative disease.
Published in a peer-reviewed scientific journal, the research examined modifiable lifestyle factors that may influence cognitive health over time. Among the findings, sleeping between seven and eight hours per night was associated with the lowest observed risk of dementia, while shorter and longer sleep durations were linked to increased risk.
Scientists have long recognised sleep as a fundamental biological process involved in memory consolidation, brain repair and the clearance of metabolic waste from neural tissue. Emerging evidence suggests that disrupted or suboptimal sleep may interfere with these processes and contribute to mechanisms associated with cognitive decline (The Lancet Neurology, 2023).
The Canadian study also explored the role of physical inactivity and prolonged sedentary time, identifying both as factors associated with elevated dementia risk. Participants with lower levels of regular physical activity and extended daily sitting time showed less favourable outcomes, supporting broader evidence that movement and exercise benefit brain health.
According to existing neurological research, regular physical activity may help maintain cerebral blood flow, reduce inflammation and support neuroplasticity—processes considered relevant in protecting against age-related cognitive impairment. Public health guidance in countries such as the United Kingdom has similarly promoted exercise as part of dementia risk reduction strategies.
An important aspect of the findings is the suggestion that dementia prevention may be influenced by a combination of behaviours rather than any single factor in isolation. Adequate sleep, reduced sedentary behaviour and consistent physical activity may work together to support long-term neurological resilience.
Researchers also noted that the relationship between sleep and dementia is complex. While sleeping too little has been associated with poorer cognitive outcomes, prolonged sleep may in some cases reflect underlying health changes rather than act solely as a risk factor itself. This distinction remains an active area of scientific investigation.
Although the study identified associations rather than direct causation, the findings contribute to a growing consensus that modifiable lifestyle factors may influence the onset or progression of neurodegenerative disorders. This has important implications for preventive health strategies as ageing populations increase worldwide.
Dementia remains a major public health challenge globally, with organisations such as the World Health Organization emphasising prevention through risk reduction wherever possible. Alongside cardiovascular health, nutrition and social engagement, sleep is increasingly recognised as part of this broader prevention framework.
Experts caution that optimal sleep is not defined by duration alone; quality and regularity are also important. Poor sleep continuity, untreated sleep disorders and disrupted circadian rhythms have all been linked in previous studies to adverse cognitive outcomes.
The findings from Canada reinforce a broader message emerging in preventive medicine: everyday behaviours can influence brain health across the lifespan. While further research is needed to clarify mechanisms and causality, maintaining healthy sleep patterns, staying physically active and limiting prolonged sedentary time may represent practical steps to support cognitive wellbeing into older age.