There is a fine thread that links our daily habits to brain health, and it is much more concrete than previously thought. It involves not just how many hours we sleep, but when we sleep, move, eat, and are active. In other words: the circadian rhythm, the biological clock that marks the 24 hours of our day, may also have a bearing on our risk of developing forms of dementia as we age.
In recent years science has begun to look at this mechanism more closely, and the results are far from marginal. A regular rhythm, well synchronized with the natural alternation between light and dark, appears to be associated with better cognitive health in the long run. In contrast, an out-of-phase, weak or irregular internal clock could be an additional risk factor.
When the body goes out of time
Circadian rhythm regulates many functions: sleep and wakefulness, hormone production, body temperature, metabolism, even attention and memory. It is not a detail; it is the conductor of the orchestra. If the conductor loses time, the orchestra goes haywire.
And that is exactly what happens when days become disordered: constantly changing sleep schedules, little exposure to natural light, activities concentrated mainly in the evening, and short, fragmented nights. This kind of disjointedness, when it becomes chronic, also seems to reflect on brain functioning in the long run.
In particular, those who have very late peak activity-those who “turn on” mostly in the afternoon or evening-show greater vulnerability than those who have more regular morning rhythms. This is not a contest of who wakes up earlier, but a matter of biological consistency.
The link to cognitive decline
The key point is that the brain does more than just work when we are awake. During sleep, and especially in the deeper stages, it activates fundamental cleaning and maintenance systems. If sleep is disturbed or out of phase with respect to the natural rhythm, these mechanisms become less efficient.
Over time, this inefficiency can promote the accumulation of waste substances and alter delicate processes such as memory, orientation, and the ability to concentrate. It is not a direct and automatic cause of dementia, but a building block in addition to many others: age, genetics, lifestyle, cardiovascular health.
Protecting the circadian rhythm could become an indirect, low-cost and side-effect-free prevention strategy. Exposing oneself to natural light during the day, maintaining stable sleep schedules, avoiding concentrating all activity in the evening hours, reducing the use of screens at night: these are simple, often underestimated steps that help the biological clock do its job.
In an age when we live perpetually out of time – always connected, always on, always late – the message almost goes against the grain. But it is clear: taking care of your daily rhythm is not just a matter of immediate well-being. It may also be an investment in brain health.
