Picture this: your house loses power and you need to find a flashlight or the fuse box. You need several moments to get used to the dark and then you are able to see better. This is called ''dark adaptation'' and it's what lets our eyes get used to the dark.
Many people don't know that night vision is dependent upon several physical, neural and biochemical mechanisms. So how does this work? The human eye absorbs photons via rod cells and cone cells, on the retina at the back of the eye. Together they form the sensory layer that helps the eye see light and color. The rod and cone cells exist throughout the retina, save for the small area opposite the pupil known as the fovea. The fovea contains only cone cells, and its main function involves focusing on detail. You might already be aware that the details and colors we see are detected by cone cells, while rod cells are sensitive to light and detect movement.
How does this apply to being able to see in the middle of the night? When you're trying to find something in the dark, like a small star in the night sky, it's much better to look at something off to the side of it. It works by using the light-sensitive rod cells.
The pupils also dilate in low light. It takes fewer than sixty seconds for your pupil to fully dilate; however, it takes about 30 minutes for the eyes to achieve full light sensitivity and, as you've experienced, during this time, your ability to see in the dark will increase remarkably.
Here's an example of dark adaptation: if you go from a very light-filled place to a darker area for example, when coming inside after spending time in the sun. Despite the fact that your eyes require several moments to get used to the darker conditions, you'll always be able to re-adapt upon returning to bright light, but if you go back into the darker setting, your eyes will need time to adjust again.
This explains why a lot people have difficulty driving their cars at night. If you look at the ''brights'' of opposing traffic, you may find yourself momentarily unable to see, until that car passes and you readjust to the night light. A good way to prevent this sort of temporary blindness is to avoid looking right at the car's lights, and instead, use peripheral vision in those situations.
If you're beginning to find it increasingly difficult to see at night or in the dark, schedule a consultation with your eye doctor who will be able to shed some light on why this is happening, and rule out other reasons for decreased vision, such as cataracts and macular degeneration.