Human study · Aging · 29 Oct 2026
More bright daytime light tracked with a lower dementia risk
Source: ScienceDaily
What the research found
Zheng and colleagues, in General Psychiatry (2026; 39(3), DOI 10.1002/gps3.70039), measured daytime and nighttime light with wrist devices in 87,577 adults. Over a median of 8.1 years, 741 people developed dementia. Average daytime light above 1,000 lux was associated with a 16 percent lower dementia risk, and more time at 5,000 lux or above was associated with further reductions. Less than 0.7 hours of bright daytime light predicted dementia more strongly, in this analysis, than six established risk factors. Nighttime light had no statistically significant association. Corresponding author Hongliang Feng is at Guangzhou Medical University. This is an association. It does not show that daylight prevents dementia. Not medical advice.
Evidence level: Human study. A study in people, but an association isn't proof of cause.
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