Getting more sunlight during the day could help protect your brain. A large study of nearly 88,000 adults found that exposure to bright daytime light (above 1,000 lux) was linked to a 16% lower risk of developing dementia. The effect was even stronger in high-risk groups, including night owls, those with high nighttime light exposure, and carriers of the APOE ε4 gene variant.
Step outside more — your brain might thank you. A large prospective cohort study published in General Psychiatry found that people exposed to daytime light levels above 1,000 lux (roughly the brightness of an overcast day outdoors) had a 16% lower risk of developing dementia compared to those with lower light exposure. And the longer the bright light exposure, the greater the benefit.
The study tracked 87,577 dementia-free UK Biobank participants over a median of 8.1 years, using wrist-worn actigraphy devices to objectively measure light exposure. Notably, daytime light exposure outperformed several well-known dementia risk factors — including alcohol use, obesity, air pollution, and hearing loss — as a predictor of future dementia.
Why it matters: Daytime light exposure is low-cost, measurable, and modifiable — making it a potentially powerful public health tool. Researchers suggest it could inform future guidelines and light-based interventions, especially for high-risk populations.
