Night blindness is a real thing and is called nyctalopia which is a condition in which someone experiences difficulty in seeing in darkness and low light conditions.
Night blindness is not a disease itself although it's instead a symptom of various eye conditions or other health issues.
When you have night blindness it means you can't see in dim or dark places and settings.
Night vision can also be bad because our eyes are not meant to see in the dark as the eyes rely on light to enter the eyes.
Our eyes rely on cone cells and rod cells to see and the eyes need the light to enter and if not enough light enters the eyes it makes it harder to see.
Although as long as we have some light in the dark we can see pretty good but some people have conditions of the eyes which make it harder to see in low light conditions such as when driving in the dark.
Some conditions that can make night vision bad and make it hard to see in low light dark driving conditions include cataracts, glaucoma, refractive errors such as nearsightedness and astigmatism and even deficiencies in vitamins.
Also aging, certain medications and prolonged exposure to sunlight can lead to poor night vision and poor vision in general.
The color of human night vision is mainly black and white.
Human eyes have rod cells which are sensitive to dim light but they also only perceive the shades of gray and not color.
The cone cells in our eyes are responsible for the color vision and are not as effective in low light conditions and is why in the dark we may notice that colors are less vibrant or even disappear entirely and then everything appears in varying shades of gray.
Humans cannot have total natural night vision although humans can adapt to low light conditions and see some in low light conditions but not total darkness.
Us humans don't possess any true night vision in the way some nocturnal animals do.
Human eyes rely on both cone cells and rod cells to see and the eyes also rely on light entering the eye to allow us to see.
The reason why some people can seek in the dark at least some is due to genetics, eye color and the sensitivity of their rod cells.
Nobody can actually see fully or truly in total darkness like they can in the day but some people can see some in total dark.
The human eye contains two types of photoreceptor cells, which are cones that are responsible for color vision in bright light and also rods which are also more sensitive to light and are also crucial for seeing in dim light conditions.
The light gets into the human eyes through the pupils in the irises and in darker light, the pupils get bigger.
A person cannot see in complete darkness.
Human eyesight relies on the light reflecting off of objects and then entering of the eye.
And in total darkness the eyes are not able to detect anything as no light is entering the eye.
Humans can adapt to low light conditions but us humans all require some form of light to see, even if it's just a small amount of light to see a little bit.
Human eyes contain rods and cones which are specialized cells that detect light.
The rods of the eyes are responsible for vision in low light conditions and the cones in the eyes are responsible for color vision as well as detail in brighter light conditions.
And in total darkness, there is no light that is being reflected or emitted, so there is nothing for the eyes to detect so we cannot see.
Also the pupils of our eyes also dilate or widen to let in more light in darker conditions, although this only works if there is at least some amount of light to gather.
And although the human brain can sometimes predict what may be happening based on any past experiences such as seeing our hands move in darkness, it's not true sight and it does not work in complete darkness.
Nocturnal animals can see in the dark and low light conditions as they have evolved special adaptations in their eyes so they can see effectively in low light conditions.
Nocturnal animals have a larger number of rod cells which are sensitive to light and motion when compared to cone cells that are responsible for color vision and also require bright light.
And many nocturnal animals also have a reflective layer called tapetum lucidum which is behind the retina, and this tapetum lucidum bounces light back through the retina and gives it a second change to detect light.
And some nocturnal animals also have eyes which are larger and have wider pupils that can also possess a slit shaped pupil for better light control.
Us humans don't have these adaptations so we cannot see very good in low light conditions and cannot see in total or complete darkness.