Up to 45% of dementia cases could be prevented or delayed by addressing modifiable risk factors, according to updated World Health Organization guidelines released this month. The figure, drawn from a review of evidence accumulated since 2019, places new emphasis on sensory deprivation, air pollution, and lifestyle habits alongside established risks such as hypertension and diabetes. For the first time, the WHO recommends hearing aids for those with hearing loss and explicitly advises against vitamin B, E, omega-3, and multivitamin supplements for dementia prevention in the absence of a diagnosed deficiency. The global economic burden of dementia is estimated at $1.3 trillion annually, half of which falls on unpaid family care.

Two sleep studies add texture to the picture of how daily rhythms influence long-term brain health. A meta-analysis from York University in Canada found that people who reported sleeping more than eight hours per night had a 28% higher risk of developing dementia compared with those sleeping seven to eight hours. Researchers caution that prolonged sleep is likely a marker of underlying conditions—such as neurodegenerative disease, depression, or sleep apnoea—rather than a direct cause. Separately, a University of Manchester study that tracked 89 adults with light sensors and sleep diaries over more than 500 days found that brighter and more consistent daytime light exposure was associated with falling asleep earlier, waking earlier, and experiencing more deep sleep in the first part of the night. The findings, published in NPJ Biological Timing and Sleep, align with the understanding that morning light helps entrain the body’s circadian clock, though the observational design cannot establish causation.

A parallel body of clinical guidance from Indonesian ophthalmologists underscores the importance of sensory development in early life. Amblyopia, or lazy eye, can become permanent if not corrected before the age of seven, the period when the brain learns to process visual signals. Doctors in Jakarta warn that children often do not complain of blurry vision because they have never known clear sight; signs such as sitting very close to the television, squinting, or frequently bumping into objects may be the only clues. The condition is not a single disease but a failure of visual function to develop optimally, triggered by uncorrected refractive errors, congenital cataracts, or strabismus. Treatment depends on the cause: glasses or patching for many, surgery only when structural abnormalities block light. Separately, clinicians note that prolonged screen use while lying down may raise myopia risk not because of radiation but because it displaces outdoor time and exposure to distant focal points and natural light.

Taken together, the findings reinforce a lifespan perspective in which sensory health and daily environmental exposures are modifiable inputs to cognitive resilience. The WHO now urges governments to integrate dementia risk reduction into national health plans, with concrete measures such as air-quality regulation and hearing-aid provision. For parents, the message from clinicians is to seek an eye examination before a child reaches school age, rather than waiting for complaints. The next research milestone will be longitudinal studies that test whether interventions to improve daytime light exposure or correct childhood vision deficits can measurably alter dementia incidence decades later.