The human retina contains light-sensitive cells. There are three types of color-sensitive cells, or cones, that allow us to perceive more than 10 million different shades of color. An additional type of light-sensitive cell in the retina, the rod cells, have a very different response to light. In normal situations, where ambient light is bright enough to strongly stimulate the cones, the rod cells play virtually no role in vision at all. However, in dim light, the cone cells are understimulated, leaving only the signal from the rod cells. The result is a sort of monochromatic vision. Put simply, in conditions of dim lighting, colors can appear ‘washed out’ or even absent. In particular, as autumn progresses and sunrise begins to come later and later, the period in the early morning wherein one’s vision is largely black and white is similarly extended.
Which is all really just a long-winded way of explaining why I am once again wearing dark navy blue socks with gray slacks.