What is the typical dark adaptation time for the human eye?

The dark adaptation time for the human eye generally falls within the range of 20 to 30 minutes, but the most accurate typical duration is often considered to be around 30 minutes for full adaptation. This process involves the gradual adjustment of photoreceptors in the retina, primarily the rods, as they become more sensitive to light in low-light conditions.

Initially, when entering darkness, the cones (which are responsible for color and detail in bright light) become less effective, and the rods start to adapt. This adaptation allows individuals to see in dim light but takes time to achieve peak sensitivity. The process involves biochemical changes within the rod cells, where the visual pigment rhodopsin regenerates from its breakdown products.

While dark adaptation can begin fairly quickly, especially within the first 10 to 15 minutes, the most significant sensitivity increase typically occurs after around 30 minutes. This is why the answer indicating 30-45 minutes aligns well with the physiological understanding of how the human eye adapts to low-light conditions over time.