The eye is an amazing organ which gathers light and converts it into electro-chemical impulses in neurons. But, it is also a complex structure consisting of a transparent lens that focuses light on the retina. The retina is covered with two different types of light sensitive cells called rods and cones.
The retina contains specialized cells called photoreceptors which are located at the back of the eye. There are two basic types of photoreceptors cells called rods and cones. The cones are the photoreceptor cells that are most sensitive to three colors red, green and blue. Cones are what your eyes use to see in daylight.
Rods are the photoreceptor cells in the retina that can function in dim light.
According to research done for The Department of Energy, the color of light has inherent qualities that have not been completely understood. They believe using light sources with spectra more like daylight but at the same light level make the pupil smaller which improves visual acuity and affects circadian rhythm.