Why is it when it is dark things look more black and white than colour?

Question: Why is it when it is dark things look more black and white than colour?
- Keywords:
  black,
  colour,
  cone,
  dark,
  light,
  retina,
  rod,
  vision,
  white
Asked by helenstride to Steve on 22 Mar 2011.
- Stephen Moss answered on 22 Mar 2011:
  
  Hi Helen
  This relates to my other answer. When it gets dark we use our rods, and the cones switch off. Rods don’t have the coloured pigments that allow us to see colour, so that’s why colours disappear in low light.

Question: Why is it when it is dark things look more black and white than colour?