What is the color of the light? I see moving blobs of blue and green etc. Or sometimes a light source that fades in and out - one light source fading away and replaced by another. The light could be of any color depending on your chakras. At a given point of time, one chakra would be more predominant than the rest and naturally the color of that chakra will be predominant. When the activity shifts from one chakra to another, the color of the chakras fade in and fade out. This happens quite frequently in charka meditation. The colors that you have mentioned belong to higher chakras. But, it is better not to concentrate on the colors as this would divert the level of your consciousness. It appears that you have achieved considerable level of spiritual progress. If you are able to move your consciousness to higher levels, ignoring these lights, probably you could be closer to self-realization.