Researchers at the University of Southern California discovered that the red, painful burn is actually damage to micro-RNA, which is then released into the skin cells signaling a solar injury—a sunburn.
This makes healthy cells stimulate the inflammatory response that inevitably causes the skin to ache and burn, reported Fox News.
The inflammatory response is created by what are known as "cytokines"—small cell-signaling protein molecules.
"The inflammatory response is important to start the process of healing after cell death," study leader Richard Gallo of the University of California, San Diego School of Medicine said in a statement, reported Mother Nature Network.
"[It] is a normal part of our protection against the sun."
This is the first time researchers have identified a step in the process of cell damage due to sun exposure.
NBC reported that the findings may not do much to help sunburn sufferers but may lead to new breakthroughs in sunscreen protection.
The study was published in the Journal Nature Medicine