nattsyn

Nattsyn, or night vision, is the ability to perceive visual information in low-light conditions. In humans, nattsyn relies primarily on rod photoreceptors in the retina, which are more sensitive to light than cones and support scotopic vision. Cones handle color and high-acuity vision in brighter illumination, while rods dominate in dim light. Dark adaptation is the process by which the retina increases sensitivity after darkness, involving regeneration of rhodopsin and adjustments in pupil size; full adaptation can take 20 to 30 minutes and yields a substantial gain in sensitivity.

Many mammals and some birds possess anatomical or cellular features that enhance nattsyn, such as a tapetum lucidum, a reflective layer behind the retina that increases light utilization. Humans, however, lack a tapetum lucidum and rely on neural processing and pupil dynamics to improve performance in low light.

Nattsyn performance varies by species and individual and declines with age. In very low light, color discrimination is limited and acuity decreases. Nyctalopia, or night blindness, is a condition in which nattsyn is diminished in mesopic or scotopic environments and can result from vitamin A deficiency, retinal diseases, or systemic conditions.

In practice, nattsyn is a central topic in vision science and ophthalmology. Technologies such as night-vision devices and low-light cameras extend nattsyn by enhancing available light and translating it into perceivable images.