"The Purkinje effect (sometimes called the Purkinje shift or dark adaptation) is the tendency for the peak luminance sensitivity of the human eye to shift toward the blue end of the color spectrum at low illumination levels. The effect is named after the Czech anatomist Jan Evangelista Purkyně.
This effect introduces a difference in color contrast under different levels of illumination. For instance, in bright sunlight, geranium flowers appear bright red against the dull green of their leaves, or adjacent blue flowers, but in the same scene viewed at dusk, the contrast is reversed, with the red petals appearing a dark red or black, and the leaves and blue petals appearing relatively bright."
via The Purkinje Effect (Wikipedia)