Scientists have figured out why green light relieves pain.

It turned out that green light activates intense signaling of gamma-aminobutyric acid - this is one of the most important inhibitory neurotransmitters of the central nervous system. Because of this, the expression of the Penk gene increases; it encodes a protein with a similar name - PENK. This substance is a precursor to the ENK molecule, which turns on opioid receptors in the brain for pain relief. The scientists tested their findings on modified mice.