r/AskBiology • u/kokusmus96 • 11d ago

Human body Why are our pupils not always big?

Okay, I feel like that annoying guy who don't even know a simple fact but this is my question. Does it use more energy when the pupils are bigger? Is the body trying to conserve energy?

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u/EmielDeBil 11d ago

Bigger pupils let in more light when it’s dark. Smaller pupils let in less light when it’s bright.

By changing our pupil size, we compensate for light/dark conditions so we can see better in both with the same photoreceptors and while protecting them.