mørktilvenningen

Mørktilvenningen is a Norwegian term that translates to "darkness adaptation" or "dark adaptation." It refers to the physiological process by which the human eye adjusts its sensitivity to light after being exposed to a bright environment and then moving into a darker one. This adaptation is crucial for maintaining functional vision in low-light conditions.

The process of dark adaptation involves several biological mechanisms. Initially, when moving from bright light to darkness, vision is poor. This is because the photoreceptor cells in the retina, specifically the rods and cones, are saturated with light. As time passes, these cells begin to regain their sensitivity. The cones, responsible for color vision and detail in bright light, adapt relatively quickly, within about 5 to 10 minutes. However, their sensitivity in very low light is limited.

The rods, which are more numerous and distributed in the peripheral retina, are responsible for vision in dim light and are much more sensitive to light than cones. Their adaptation process is slower, taking 30 minutes or more to reach full sensitivity. During this time, the concentration of rhodopsin, a light-sensitive pigment in the rods, increases. Rhodopsin is bleached by bright light, and its regeneration is essential for improved vision in the dark. Complete dark adaptation allows individuals to see objects that would be invisible after only a few minutes in the dark. Factors such as age, vitamin A intake, and certain medical conditions can affect the efficiency of dark adaptation.