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How Humans See At Night

Why Can’t We Humans See Clearly At Night? (The Sad, Evolutionary Reason)

If you know how eyes work, then you know they require light to see.

So, how are we able to see so well in the dark?

Our eyes can see a remarkably broad range of lighting conditions because of different areas of the eye functioning together.

Keep reading to learn how our eyes see at night and how you can increase your night vision abilities.

You can also read our reviews for the best thermal imaging scopes especially useful for night hunting.


How Do We See In The Dark?

The eye in the dark

Our vision range in different light conditions comes from three parts of the eye:

  • The Pupil: The eye in several ways is similar to a camera. The aperture of the camera is the component that contracts and expands to allow in less or more light. The pupil works similarly. It will open wide in the darkness and will become really little to block the amount of light reaching the retina. Shine a flashlight at somebody's eyes, and you can see this process in action (but make sure to notify them first).
  • Cone and Rod Cells: Our eyes use two unique kinds of cells to see the light: rods and cones. The cone cells see fine detail and color but require bright light to do so. Rod cells have poor resolution and can only see white and black, but stay sensitive in very low light. A white barely perceived by the rods must be increased in brightness 1,000 times until the cones can pick it up.
  • Photopigments: Both rods and cones contain light-sensitive compounds called photopigments. When subjected to light, photopigments undergo a chemical process that transforms light energy into the electrical activity our brains know how to interpret. Rhodopsin is the key to night vision and is the photopigment used by the rods and. Light causes these pigments to glow, reducing sensitivity. Darkness makes the molecules to regenerate in a procedure known as" dark adaptation" where the eye adjusts to see from the very low lighting conditions.

Prepare Your Eyes To See In The Dark

improve night vision

It's much easier for our eyes to adapt to intense light than to adjust for the darkness.

Cones achieve maximum sensitivity to seven minutes, while sticks need thirty to forty-five minutes or more of the night to make 80% dark adaptation.

Total adaptation can take hours.

If you want to accelerate the process, here is a couple of hints:

  • Wear sunglasses. A couple of hours of exposure to bright sunlight may lower your ability to adapt the darkness by ten minutes, and ten days of exposure can cause a 50% reduction in night vision. Make sure to wear glasses with grey color to block out the complete visible spectrum, and the darker the lenses are, the better. Before going into the low light, wearing red-tinted eyeglasses for 20-30 minutes can help because rod cells don't pick up the color red.
  • Reduce the brightness on your computer display. By keeping the brightness on your TV or computer low, your eyes won't need to adjust as much.
  • Never look directly at bright lights. Gazing straight at a bright light can significantly increase the amount of time that your eyes will need to adjust to the darkness. Consider closing one eye to keep some dark adaptation if you have to look towards a light. Try not to look at beams coming towards you when driving at night and look to remain on course and look to the lines in the road to stay on course.
  • Let your eyes adjust freely. Before going to a dark region and risking bouncing into something, close your eyes and cover them for some time to allow them to adapt. Additionally, applying slight pressure with your palms can help accelerate the adjustment procedure.

Being able to see at night is essential for your safety and your convenience.

To help preserve your night vision, make sure to get enough vitamin A, avoid smoking, and wear sunglasses outdoors.

About the Author Rob Carson

I work in commercial construction, in Dallas, TX.

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