...
By Melissa Fleur Afshar
Reporter
0
Share
Newsweek is a Trust Project member
See more of our trusted coverage when you search.Prefer Newsweek on Googleto see more of our trusted coverage when you search.
Spending more time in bright daylight could help protect the brain from dementia, according to new research that tracked light exposure in nearly 90,000 adults over eight years.
Researchers in China found that people who got more moderately bright daytime light had a significantly lower risk of developing dementia than those who did not, while nighttime light exposure made no measurable difference. The findings point to light exposure as a simple, modifiable factor that could be added to existing strategies for reducing dementia risk.
Newsweek spoke with Dr. Dayan Goodenowe, a neuroscientist and author of Breaking Alzheimer's, known for his research into prodromes, the early biochemical indicators of disease, who said the study fits into a broader picture of brain health and longevity.
Read More on Health
"From my vantage point, this study reinforces the idea that Alzheimer's disease is influenced by multiple modifiable factors and healthy brain function depends on many interconnected systems," Goodenowe said. "As I point out in my lectures, these things include circadian regulation, sleep, metabolism, membrane biology, and nutrition...all work together to support the body and brain."
...
Goodenowe, who developed the first bioavailable plasmalogen solution, said his own research centers on plasmalogen biology and restoring brain cell membranes, but that the new findings add another important piece to the puzzle.
"Maintaining healthy daytime light exposure represents another potentially important component of overall brain health...and the body, overall," he said.
How the Study Was Conducted
For the study, researchers measured daytime and nighttime light exposure in 87,577 dementia-free adults, with an average age of 62, using wrist-worn accelerometers over seven days of normal activity. Participants were then tracked for a median of 8.1 years, during which 741 people developed dementia. Cases were identified through primary care records, hospital admissions and death registry data.
Average daytime light exposure above 1,000 lux, roughly the brightness of an overcast day outdoors, was linked to a 16 percent reduction in dementia risk. Longer exposure to brighter light, of at least 5,000 lux, was tied to an even further drop in risk.
Notably, getting less than 0.7 hours of bright daytime light per day was a stronger predictor of dementia than six established risk factors for the disease. Nighttime light exposure showed no significant link to dementia risk either way.
What the Results Mean
Further analysis suggested that circadian rest-activity rhythms and brain structure changes could account for up to a third of the protective association, hinting at how daytime light might influence the brain.
The protective effect of daytime light was strongest in certain groups, including those with higher nighttime light exposure, an evening chronotype, or those carrying the APOE ε4 gene variant, which is linked to higher Alzheimer's risk. For these participants, the risk reduction reached as high as 41 percent.
"Daytime light exposure may serve as a novel indicator of dementia risk," corresponding author Hongliang Feng, from Guangzhou Medical University in China, said in a statement when the study was published in General Psychiatry.
The researchers said the findings support further investigation into daytime light exposure as a low-cost, accessible tool for dementia prevention, alongside other known lifestyle factors. The results also add to a growing body of evidence that shows a connection between Vitamin D exposure, circadian regulation and dementia risk, among other lifestyle factors.
Contact Newsweek editors on this story: Kara Dolman and Gray R. Thomas
View 0 Comments
Submit Correction
View Editorial & AI Guidelines