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.
However, consuming a large amount of caffeine daily or more than 250 mg of caffeine at a time can cause some unwanted effects. Too much caffeine can act to can speed up the heart rate, which can be dangerous for those with diabetes and heart problems. Those suffering from heart disease should limit their intake of caffeine to avoid experiencing any problems.