Most people are aware, even if they don't realize it, that light is the source of all color. In 1666 Sir Isaac Newton performed his famous optics experiment. He set up a prism in a dark room and allowed a ray of light to pass through it. The white light bent and the screen he had set up was filled with the colors of the rainbow, thus proving that light is filled with color.
While most people are familiar with the idea that God is love (1 John 4:8), far fewer are aware that the Bible also declares that God is light (1 John 1:5) and that He is the Father of lights (James 1:17). These scriptures go on to say that there is no darkness, nor even any shadow in Him. If God is light, then he is also color as all color exists within light. When Satan was cast out of heaven, he became disconnected from the source of all light and though he may attempt to appear as an angel of light (2 Corinthians 11:14), he is now a creature of darkness. When Moses spent time in the presence of God, he began to glow (Exodus 34:29-35) but that glow would fade away as time passed outside of God's presence. In like manner, Lucifer shone brightly (see Isaiah 14:12) prior to his fall, but that light would have begun to fade when he became known as Satan and was cast out of the presence of the Lord. Like a flash of lightning, the light he had displayed was brilliant for a moment and then gone (Luke 10:18).
We also know that Satan is not a creator, but rather a counterfeiter and corrupter. For these reason when our dreams are filled with light and color, their source is certainly from God and when they are black and white, devoid of light or have only muted colors, they are from the enemy. Try as he may to instill color into the world of our dreams, the best Satan can do is muted and dull due to his lack of light, the source of color.
When you go to the movies or sit to watch television, it is the pixels of light projected onto a screen that allow us to "see" the images we call video or moving pictures. When we dream we are "watching" a movie made up of pixels of light created and observed in the spiritual dimension rather than the natural world. You may have been taught in school that the smallest pieces of creation were the building blocks of atoms - protons, neutrons and electrons. However, today science has proven that there are even smaller particles called quarks and while the science is complicated and the following statement may be oversimplified - quarks are made up of light. The end result is that everything around you that we consider solid and natural is made of light. When God spoke the words, "Let there be light" (Genesis 1:3), he created all things by releasing a part of Himself to "make" them.
Why is light important to the understanding of dreams? The images of our dreams are created from light revealed when the window of the spiritual realm is opened up for us. At the same time, everything that exists around us in the natural realm is also made of light. Understanding light is important to our understanding of dreams because, our dreams are just as real and have just as much impact upon us when we understand them as does the natural world around us.