Why do your pupils in your eyes get smaller when you look in the light?

Question: Why do your pupils in your eyes get smaller when you look in the light?
- Keywords:
  eye,
  light,
  pupil
Asked by lola :) to Fiona, Hazel, Jacque, K, Matthew on 15 Mar 2018.
- K Sasitharan answered on 15 Mar 2018:
  
  It is a form of adaptation of the eye to various levels of lightness and darkness. When you look into light, the pupils constrict (get smaller) so that a lesser intensity of light enters your eye.

Question: Why do your pupils in your eyes get smaller when you look in the light?