A recent study highlights the importance of circadian rhythms for long-term brain health, particularly in older adults. The research, conducted in 2025 with over 2,000 participants averaging 79 years old, revealed that individuals with strong circadian rhythms had nearly half the risk of developing dementia compared to those with weaker rhythms. Circadian rhythms regulate various daily processes, including sleep timing, hormone release, heart rate, and body temperature.
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The study followed participants for three years and found that those with disrupted circadian rhythms were more likely to develop dementia. Disruptions in these rhythms are often linked to poor sleep, which has long been associated with dementia and heart disease due to shared risk factors.
While the study did account for factors such as heart health and high blood pressure, sleep apnoea was not included in the analysis. This condition causes intermittent pauses in breathing during sleep, leading to reduced oxygen supply to the brain, and is associated with high blood pressure. The link between sleep apnoea and dementia remains contentious, as it is often more prevalent among people with existing dementia risk factors, such as obesity and diabetes.
Experts suggest that tackling physical inactivity resulting from fatigue associated with disrupted sleep may help. Increasing physical activity could combat obesity, enhance sleep quality, and support brain cell health, potentially reducing dementia risk through multiple avenues.