Web Desk: Spending enough time in natural daylight each day could reduce the risk of dementia by up to 25%, according to a new study conducted by researchers in China.

The study, carried out by researchers from several Chinese universities, followed nearly 87,600 participants over an eight-year period. The average age of the participants was 62, and their daily physical activity and exposure to sunlight were monitored using wrist-worn actigraphy devices equipped with light sensors and accelerometers.

During the study, 741 participants were diagnosed with dementia. Researchers found that people who spent most of their time indoors in dimly lit environments had a higher risk of developing the condition. However, those who were exposed to brighter natural light experienced a 15% to 25% lower risk.

According to the findings, spending time in daylight with an average light intensity of at least 1,000 lux—similar to a well-lit room or an overcast day outdoors—was associated with a 16% reduction in dementia risk.

The study also found that spending around 90 minutes a day in natural light of 3,000 lux or more was linked to an 18% lower risk, while 40 to 45 minutes daily in very bright light of 7,000 lux or higher was associated with a 17% reduction.

Researchers noted that getting less than 42 minutes of strong natural daylight each day was a stronger predictor of dementia than several well-known risk factors, including obesity, alcohol consumption, and traumatic brain injury.

The protective effect of daylight was even greater among people exposed to more artificial light at night, which can disrupt sleep. Poor sleep quality is already known to increase the risk of dementia.

The study further revealed that adequate daytime sunlight reduced dementia risk by 30% to 38% among people with high nighttime light exposure. Among individuals who regularly stay awake late at night, sufficient daytime sunlight was associated with up to a 40% lower risk of developing dementia.

The findings were published in the medical journal General Psychiatry, highlighting the importance of regular exposure to natural daylight in supporting brain health and potentially lowering the risk of dementia.