How do your eyes adjust when moving from dark to light?

When you move from darkness into bright light, your eyes adjust through a process called light adaptation. First, the pupils constrict rapidly, reducing the amount of light entering the eye. This happens within seconds due to the pupillary light reflex controlled by the iris muscles. At the photoreceptor level, the rod cells, which are highly sensitive and used in dim conditions, become temporarily overwhelmed and bleach out their photopigment rhodopsin. The cone cells, which handle bright light and color vision, then take over. The visual system also reduces its overall sensitivity by adjusting neurotransmitter release and signal processing in the retina. Full light adaptation typically takes about five minutes, much faster than dark adaptation, which can take up to 30 minutes.