What do you see when you close your eyes? Try it right now – you’ll notice that there’s probably quite a light show happening, one that is constantly changing.
Interestingly, we don’t need light to stimulate our visual systems. The neurons in our visual system are busily sending signals to the brain via what’s known as the thalamus. So, even when we are in total darkness, just resting our eyes or even when we are asleep, there’s always something to see.
In fact, this constant activity can create splashes of colour or patterns that can change quite randomly. The frequency, duration and types of effects can all be affected by which neurons are being stimulated at any given time. The technical term for this visual experience or phenomenon is called ‘phosphene’.
These phosphenes can be heightened by all kinds of everyday stimuli, such as an intense sneeze, hearty laughter, coughing, blowing your nose or standing up too quickly. Other factors such as low blood pressure or low oxygen intake can increase the visual show even further, and certain drugs like LSD can take it off the scale.
Another way to induce a charge of activity is to apply some light pressure on the eyelids when closed. This pressure triggers a different pattern of light activity and, all of a sudden, a whole new light show can be induced in a fraction of a second because the brain believes it is seeing a form of light.
A further form of phosphene is called a ‘closed-eye hallucination’. This happens either through chemical use or a form of meditation.
There are five levels:
There’s no doubt that humans have a lot to ‘see’ even when we close our eyes. Phosphenes are a combination of mechanical, electrical or magnetic stimulation that, even though they are considered a phenomenon, are very real.
In other words, anytime you want to see something spectacular, just try closing your eyes.