Higher Daytime Light Exposure Linked to Lower Dementia Risk

A large-scale study has found a significant association between higher levels of daytime light exposure and a lower risk of developing dementia later in life. The research, published in the journal General Psychiatry, followed nearly 88,000 adults for a median of over eight years.

Participants, who were around 62 years old on average and did not have dementia at the start, wore wrist-worn devices equipped with light sensors for seven days to measure their exposure during normal daily activities. Over the follow-up period, 741 individuals developed dementia, with cases identified through health records.

The analysis revealed that average daytime light exposure above 1,000 lux-roughly equivalent to the brightness of an overcast day outdoors-was linked to a 16 percent reduction in dementia risk. Longer exposure to brighter light, at levels of at least 5,000 lux, was associated with an even greater protective effect. Notably, the study found that getting less than about 42 minutes of bright daytime light per day was a stronger predictor of future dementia than six established risk factors, including obesity, alcohol consumption, and traumatic brain injury.