Why can insufficient lighting cause eyestrain and discomfort?

In the context of interior design, insufficient illumination is a significant health concern because it forces the eyes to work harder to perceive details, leading to asthenopia, or eyestrain.1

When lighting is inadequate, the eyes struggle to perform visual tasks, which can result in physical discomfort such as pain in the eyeball, frontal headaches, blurred vision, and smarting or watering eyes. These symptoms are often exacerbated by close-up work, such as reading, as the eyes attempt to compensate for the lack of light.2

To mitigate these issues, interior designers and illuminating engineers utilize established standards for illumination levels and implement controls to shield the eye from direct glare. Proper design strategies—such as using lampshades as light diffusers, incorporating architectural lighting, and ensuring a balance of highlights and shadows—are essential to maintaining visual comfort and health within an interior space.1