Bright Artificial Light in the Evening May Increase the Risk of Glaucoma and Cataracts

Exposure to bright artificial light during evening hours may be associated with a higher risk of developing serious eye diseases later in life, according to a study published in the journal GeroScience.

The researchers found that the greatest risk was linked to exposure to high-intensity light—more than 1,000 lux—between approximately 8:00 p.m. and 11:30 p.m. Participants exposed to this level of illumination were more likely to develop age-related macular degeneration, cataracts, and glaucoma.

The authors emphasize that the findings do not apply to typical household lighting. Standard indoor lighting generally ranges from about 100 to 500 lux, well below the threshold identified in the study. Potentially concerning exposure levels may occur under brighter conditions, such as intense screens, professional lighting systems, or certain workplace environments.

The study analyzed data from more than 82,000 participants in the UK Biobank. Individuals who already had eye diseases at the beginning of the study were excluded so that researchers could focus on newly diagnosed cases.

Participants wore monitoring devices for one week that continuously recorded both light exposure and physical activity. Their health was then tracked for an average of approximately eight years.

The analysis revealed a clear dose-response relationship. Regular exposure to evening light levels above 1,000 lux was associated with a 31% higher risk of Age-related Macular Degeneration, an 18% higher risk of Cataract, and a 47% higher risk of Primary Open-Angle Glaucoma. The longer participants were exposed to bright light in the evening, the greater the observed risk.

Researchers note that the eyes are involved not only in vision but also in regulating the body's circadian rhythms. Disruption of these biological rhythms, together with exposure to blue light emitted by modern LED-based light sources, may contribute to oxidative stress and damage to sensitive cells in the retina and lens.

The authors suggest that evening light exposure could represent a modifiable risk factor, making it a potential target for prevention strategies. Possible measures include reducing screen brightness, limiting exposure to intense artificial lighting late in the evening, and using softer, warmer lighting before bedtime.

However, the researchers stress that the study was observational. While it identified a significant association between evening light exposure and eye disease risk, it does not prove that bright light directly causes these conditions. Further research will be needed to clarify the underlying biological mechanisms and determine whether reducing evening light exposure can lower long-term risk.

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