Less than 42 minutes of bright daylight linked to higher dementia risk

Getting more daylight could be linked to a surprisingly powerful benefit for brain health. In a study of more than 87,000 adults, researchers found that higher daytime light exposure was associated with a 16% lower risk of dementia, with longer exposure to bright light linked to even greater reductions. Remarkably, getting less than 42 minutes of bright daylight daily was a stronger predictor of dementia than six established risk factors. Could the amount of daylight you get each day offer clues about your risk of developing dementia? A large new study suggests that exposure to brighter daytime light is associated with a lower likelihood of developing the condition.

The findings, published in General Psychiatry, point to daytime light exposure as a potentially overlooked factor in brain health. To investigate the connection, researchers analyzed data from 87,577 adults who wore wrist devices equipped with accelerometers. The devices allowed scientists to measure participants' exposure to light during both the day and night. Over a median follow-up period of 8.1 years, 741 participants developed dementia. The results revealed a notable pattern. People exposed to average daytime light levels exceeding 1,000 lux (a moderately bright light level