Khaberni - A recent study has shown that increased exposure to daylight may help reduce the risk of dementia.
Regular exposure to natural lighting during daylight hours has been linked to a significant reduction in the likelihood of developing the disease, even among individuals who are genetically at higher risk or who suffer from sleep disorders.
The study was conducted by researchers from Chinese universities, who followed approximately 87,600 people with an average age of 62 over eight years. Participants wore devices on their wrists that measured light exposure and physical activity, and during the follow-up period, 741 individuals developed dementia.
The results showed that individuals who spent most of their time in dimly lit environments were more prone to developing dementia, while transitioning to brighter environments led to a reduction in this risk by between 15% and 25%.
It was also found that exposure to an average daylight intensity of over 1000 lux, equivalent to moderate indoor lighting or cloudy day outdoor light, was associated with a 16% lower risk of dementia compared to those exposed to lower light levels.
The study noted that spending about an hour and a half daily in light of an intensity of 3000 lux or more, equivalent to daylight, was associated with an 18% lower risk of developing dementia. Exposure to very bright light with an intensity of 7000 lux or more for about 40 to 45 minutes daily decreased the risk by 17%.
The researchers pointed out that being exposed to bright daylight for less than 42 minutes daily was a stronger indicator of dementia risk than six known risk factors, including obesity, alcohol consumption, and brain injuries.
The benefits were more evident in individuals exposed to light at night, which can negatively affect sleep quality. Getting sufficient daylight was associated with a reduction in dementia risk ranging from 30% to 38%, despite exposure to nocturnal light.
The risk of developing dementia decreased by 40% among individuals who preferred staying up late and sleeping at delayed times when exposed to more daylight.
The results also showed that individuals carrying a genetic mutation that significantly increases the risk of Alzheimer's disease benefited from daylight exposure, as it was associated with a decrease in dementia risk ranging from 19% to 27%.
The researchers explained that light exposure is one of the most important factors regulating the body's biological clock, which controls the sleep-wake cycle and several cognitive functions. They suggested that improving the function of the biological clock and sleep quality could be one of the reasons explaining the protective relationship observed in the study, and previous research indicated that adequate daylight exposure could help prevent shrinkage of certain brain regions associated with dementia.
Despite these results, the researchers emphasized that the relationship between light exposure and dementia risk still requires further studies to confirm it; however, they considered that daylight could represent a simple and low-cost means to support brain health, which can be taken into account when setting public health guidelines for dementia prevention.
