Why do we see colour when we close our eyes?

Roberta Torricelli

Although quite surprising and perhaps even a little spooky, seeing colours when we close our eyes is absolutely normal.

Try now and close your eyes, what is the first thing you see?

The majority of people will tell you that they see splashes of colours and/or flashing lights against a dark, almost black, background.

Now try again, but this time rub your eyes… what happens to the lights? In most cases, they suddenly become brighter and intensify until, a few seconds later, they return to their initial appearance.

This phenomenon is known as “phosphene” and the simple explanation as to why this happens is that our visual system (eyes, nerves and brain) do not simply stop working if light is removed. Think of it as if you were to put a cap on a camera lens.

These lights can be described as “retinal noise”, with the retina being the light sensing component of our eyes. As a matter of fact, scientists believe that the lights and colours you “see” with your eyes closed are in fact, self-generated light or in other words, biophotonic light. This is like the light generated by fireflies!

This is possible because the atoms that make up our body are constantly absorbing and emitting light, or biophotons (bio in this case means from our body), as a result of normal biochemical and cellular interactions. Our eyes however, are not designed to distinguish between light from the outside world and self-generated light, which means that even when they are shut, information is still transmitted to the brain, where it is interpreted and recognized. This might explain why people that are born blind from birth don’t experience this burst of lights and colours, but people that have become blind do, because their brains have been exposed to light stimulation and have been able to convey meaning to it.

The reason why rubbing our eyes intensifies the phosphenes is because the pressure from rubbing generates an even higher number of biophotons release in several different regions of our eyes. Although, scientists believe that our eyes and retina aren’t the only places capable of producing “visible” biophotons, but rather that different areas of our visual system, for example our optic nerve and optic tract, can in fact also generate them and stimulate our visual cortex. This perhaps might explain why certain blind people retain the ability to see “see” and perceive the world around them.

Different types of phosphenes have also been recorded. Sometimes you might experience blobs of lights, sometimes you may witness shapes and spirals. This will all depend on the properties of the biophotons released as well as the nature of the stimulus needed to release them, such as rubbing your eyes or moving them around while you keep them closed.

Although we still don’t have a clear understanding of how this process works, and of which stimulation results in the release of which biphotons, it still holds potentially valuable insights for the treatment and management of blindness.