The retina contains what are called rods and cones. These photoreceptors are sensitive to light. In a study in rats by the Chinese Institute of Neuroscience, these receptors were turned off at different times. This enabled the researchers to monitor how the experience of pain changes.
Photoreceptors send signals to cells within the retina. These cells are affected by the type of light that shines on the eyes. If this light is green, more substances that slow down the nervous system are released.
Slowing down the nervous system activates a protein called PENK. This protein, in turn, activates opioid receptors in the brain. These receptors can bind to opioids (painkillers) and thus reduce pain.
In short: When we see green light, the cones send a signal to the cells in our retina, which slows down our nervous system. This activates a protein that ensures that analgesic substances (such as morphine and your body’s own endorphins) can bind to pain receptors. When this bonding occurs, we feel less pain.
The research has been published in the scientific journal Translational Medicine Sciences. Scientists want to research further why the brain evolved in a way that green light could reduce the perception of pain.
