why can"t we distinguish colours in dim light?

Cells sensitive to light cover the inner eye.   The human eye has two types of these photoreceptor cells, rods and cones .   Cones, located in the fovea, respond to bright light and color.   Pigments vary in the cones making different cones sensitive to the varying wavelengths of light.   Rods are abundant in the retina and are sensitive to dim light.   Rods also detect changes in the intensity of light across the field of vision and thus aid in the perception of movement.   Rods cannot distinguish color while cones are insensitive in dim light.   This is why it is difficult to see colors in dimly lit rooms.