Unless there is something really wrong with you, your eyes cannot change color, unless there has been prolonged exposure to sunlight. All of what we see around us is REFLECTED light. When you look at an object or even another person, you are actually receiving reflected light into your eyes. If that object was illuminated with red light, you would see that object as red, even though it may in fact be white. The melanocytes of the iris do not change (except in infants and the elderly) and therefore are not responsible for periodic eye color changes. The light around you does change, however, especially reflected light....from the color of the room, the sky, and your clothes." It turns out that eye color in humans is more complicated. At least two genes control eye color and they work in complicated ways. There may be more genes involved. Sometimes when you are angry or sad, your eye will dilate more or less which will change how your eye is reflecting light and can cause it to appear lighter or darker.