Do Humans Have Built In Night Vision?
Is it possible for people to see in the dark? Are some people better at it than others? Well its a question we have all wondered about at some point and its usually when we are stuck somewhere without a flashlight. The simple fact is that humans do actually have quite good night vision to a point but not when we are compared to some animals such as cats and other night predators.
Unlike animals we can only see visible light in one spectrum where as many animals can see into the ultraviolet or infrared spectrum which means they dont have to rely on the moon or any other natural light sources. Felines like the common house cat are also much better at making use of available light by bouncing it from the back of their eye to the front again to magnify any image. This is contrasted ours eyes which only use about 10% of the available light.
So it may seem that animals are miles ahead of us when it comes to moving around in darkness but this is not strictly true. Most peoples assumption that we have no night vision mainly comes from the fact that we do not get our night vision instantly as some animals do. Rather we have to wait for between 20-30 minutes to get true night-vision, however your eyes do naturally start to adjust within minutes. Once you have left the necessary time for your eyes to adjust then you will actually be able to see quite well, however this will depend on there being some available light and so we may struggle on a cloudy night for example.
The actual biology of our night vision comes from a chemical in the rods of our eyes called Rhodopsin. This chemical is very sensitive to white light and actually bleaches the rods in your eyes to pick it up better. This process can take a maximum of 30 minutes which explains why we do not get night vision instantly.
Do people actually use night vision often or even in their daily job? Well apart from sheppards it may not seem that obvious. However you may be surprised to find that soldiers in the army use it quite often even though it is mainly the special forces. You may think that anyone in the army will have access to proper night vision goggles however they are often found to be clumsy and not that practical especially if you are on long trips at night. In his 1996 book Bravo Two Zero about the first Iraq war the British SAS soldier Andy McNabb details his journey behind enemy lines as they worked to infiltrate the country.
Mr McNabb recounts that they only travelled at night to avoid capture and only using their own night-vision to navigate. He says that none of the special forces soldiers took electronic night vision goggles as they were too heavy a clumsy to carry around and that after years of training at night his own night-vision was almost as good. He does however tell of the one serious problem with human night vision in that once you see a bright light your eye reacts and your eyes are back to normal again. To combat this he says he used to read his maps with one eye closed so he only ever lost night-vision in one eye at a time.
As you can see we are no match for the cats or rabbits of this world however given the chance the human body seems to find a way to adapt to its surroundings. Who knows maybe one day we will have better vision than all animals combined, maybe even x-rays!