Daytime Bright Light Tied to Lower Dementia Risk, Study Finds

A study of 87,577 adults found that bright daytime light was linked to a 16% lower dementia risk at exposures above 1,000 lux and 17% lower with at least 42 minutes at 5,000 lux or more. Over a median 8.1 years, 741 participants developed dementia. Too little bright daytime light was a stronger predictor than obesity, alcohol use and traumatic brain injury.

• 87,577 adults wore light sensors for 7 days; follow-up averaged 8.1 years
• Daytime exposure above 1,000 lux linked to 16% lower dementia risk
• 42+ minutes at 5,000 lux or higher linked to 17% lower risk
• Nighttime light exposure showed no significant association with dementia