What is night vision?

Night vision, also called scotopic vision, is your natural ability to see in the dark. It kicks in when different components, in particular your pupils and retinas, work together inside your eyes. It can come in pretty handy when you need it.

How your eyes adjust to darkness

In a dark setting, your eyes like to gather as much light as possible. They do this by opening the pupils wide and allowing your eyes to catch as many rough outlines and shapes as they can.

In a brighter setting your pupils shrink back down, since they have all the light they need to see comfortably.

To witness this firsthand, stand in front of a mirror in a darkened room, then ask someone to turn on the lights. If you’re fast enough, you’ll see your pupils quickly shrinking.

This automatic process is one reason you have scotopic vision, but it doesn’t show the entire picture. For that, you have to look at the microscopic cells in the back of your eyes.

There are millions of rod-shaped and cone-shaped cells along every eye’s retina. These rods and cones are necessary for eyesight.

Rods and cones each react a little differently to varying types of light. When the right light strikes them, they send tiny impulses along your optic nerve and into the back of your brain. This is how vision happens.

While cones are great at registering bright lights, colors and fine details, they’re not so useful for helping you see in the dark — that’s where your rods come in.

Rods excel in peripheral vision and are much more sensitive to light photons, which makes them extremely helpful in low-light settings. Without rods scattered across your retinas, any sort of darkness would be virtually blinding.

But there’s a catch: Rods can’t process color. This is why your night vision usually isn’t very colorful and often seems to be in black and white.

Look around next time you’re lying in a darkened bedroom. Not very vibrant, is it?