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Home » What’s New » In the Middle of the Night: Seeing in the Dark

In the Middle of the Night: Seeing in the Dark

It's happened to all of us: there's a power outage and suddenly, you need to find a flashlight or the fuse box. Your eyes normally require a few minutes to adjust to the dark and then you can see again. This process, ''dark adaptation,'' causes our eyes to see even when it's really dark.

Many people don't know that night vision relies on the cooperation of physical, neural and biochemical mechanisms. Let's have a look at how this works. The retina is a layer of cells at the back of the eye. The section of the retina directly behind the pupil that is responsible for the point of focus is called the fovea. The retina comprises cone cells and rod cells, named for their respective shapes. The rods are able to function even in low light conditions but those cells are absent from the fovea. What's the difference between rods and cones? Basically, cones help us see color and detail, while rod cells are sensitive to light and detect movement.

Considering these facts, if you're trying to get a glimpse of something in the dark, instead of focusing right on it, try to use your peripheral vision. By looking to the side, you take advantage of the rods, which work better in the dark.

Another process your eye undergoes is pupil dilation. The pupil dilates to its largest diameter within a minute; however, your eyes will get better at seeing in the dark over a half hour time frame. During this time, your eyes become 10,000 times more sensitive to light.

Here's an example of dark adaptation: if you leave a bright area and enter a dim one, for instance, when you go inside after being out in the sun. Despite the fact that it takes a few noticeable moments to begin to see in the dark, you'll quickly be able to re-adapt to exposure to bright light, but then the dark adaptation process will have to begin from scratch if you go back into the dark.

This explains one reason behind why many people have difficulty driving their cars at night. When you look right at the lights of opposing traffic, you are briefly unable to see, until you pass them and you once again adjust to the night light. To prevent this, don't look right at headlights, and instead, try to allow peripheral vision to guide you.

If you find it challenging to see when it's dark, book a consultation with our doctors who will see if your prescription needs updating, and rule out other reasons for decreased vision, such as macular degeneration or cataracts.