Iris (Definition) The iris is a structure within the eye that helps reduce the amount of light that reaches the retina. The iris is known as the colored part of the eye, and can be blue, brown, or any color or combination of colors in between. The iris is the portion of the eye that responds to light stimulation. ...Read more.
Scientists also speculate that caffeine may provide a mood-boosting effect that helps ease pain. Regardless of the mechanism by which it works, the data does indicate that caffeine does indeed make pain medications more effective and help ease pain.
There are two theories. The first: A headache happens when the body releases adenosine, a chemical that inflames blood vessels, causing throbbing and pain. The caffeine in coffee puts the kibosh on adenosine and helps constrict blood vessels. The second theory posits that caffeine increases the effectiveness of pain relievers, helping the body absorb them more quickly for faster relief.