The pupil mirror

Study your pupils in the mirror. What happens at red, white or blue light? Why do your pupils shrink in bright sunlight, and get bigger when you are in a dark room?

The pupil lets light enter the eye’s iris. The pupil looks black as the light that hits the pupil is absorbed by the eye’s tissues. A pupil’s size is regulated by spontaneous contractions and expansions of the iris so it can adapt the amount of light that enters the eye. The pupil decreases as light levels increase, and increases as light decreases.

The size of the pupil can also change if a person is under the influence of drugs, or in love. When a person is in love, the pupil becomes larger because of endorphins in the body. Endorphins are hormones produced by the body. Endorphins relieve pain and affect our need to sleep, eat and drink. Endorphins are released when we laugh, are stressed, exercise, have sex or are in love.

Here, you can learn more about the eye.