Purkinje effect

The change in the colour sensitivity of the human eye that occurs when dark adaption takes place. In daylight, a normal eye detects light in the wavelength range 400-750 nanometres, the peak sensitivity lying in the yellow to green region. Under low levels of illumination, the eye adapts to increase overall sensitivity to light, but is less able to detect the redder end of the spectrum; the peak sensitivity moves further towards the green.