Simple daily sunshine habit could cut dementia risk by up to 40% | Science | News
Spending more time in daylight may play a role in reducing the risk of developing dementia later in life, new research suggests.
Analyzing data from nearly 87,600 adults, scientists found a consistent link between higher levels of daytime light exposure and a reduced likelihood of developing the condition.
The study, conducted by researchers at universities in China and published in the journal General Psychiatry, followed participants for nearly eight years. The average age was 62 and all wore wrist-mounted devices that measured both movement and light exposure.
During the study, 741 participants were diagnosed with dementia.
Researchers found that people who spent more time in brighter environments throughout the day had a significantly lower risk of developing the condition compared to those who lived in dimly lit indoor environments.
Those exposed to average daytime light levels above 1,000 lux (roughly equivalent to a brightly lit indoor space or a covered outdoor day) had a 16 percent lower risk of dementia.
Spending about 1.5 hours a day in light above 3,000 lux, similar to outdoor daylight, was associated with an 18 percent reduction in risk, while spending 40 to 45 minutes in very bright light above 7,000 lux was associated with a 17 percent decrease, the Daily Mail reported.
Overall, spending less than 0.7 hours per day in bright sunlight appeared to be a stronger predictor of dementia risk than several established factors, such as obesity, alcohol consumption and traumatic brain injury.
The protective effect of daylight became even more evident in people exposed to high levels of light at night, which is known to disrupt sleep patterns. Poor sleep quality itself has been linked to dementia risk.
Even among those exposed to more light at night, higher daytime light levels were still associated with a 30 to 38 percent lower risk of dementia, the researchers said.
This effect was also seen in animals called “night owls”; People who got more daylight saw a 40 percent reduction in risk.
Even individuals carrying genetic mutations associated with a higher risk of Alzheimer’s disease showed benefit; daylight exposure was linked to a 19 to 27 percent lower risk.
Light exposure serves as an important signal for the body’s circadian rhythm (an internal 24-hour clock that regulates sleep, wakefulness and cognitive function), the researchers said.
While the study showed an association rather than a cause-and-effect relationship, the authors said the findings suggest that light exposure may be a useful marker in future dementia research.
They added that increased exposure to light during the day could potentially support brain health by improving circadian rhythm function and sleep quality.
Researchers have also suggested possible biological mechanisms, including the role of disrupted circadian rhythms in neurodegenerative diseases and early evidence that light exposure may help slow the loss of brain volume linked to dementia.
However, they emphasized that more research is needed before definitive conclusions can be drawn.
