Eyes Closed, Mind Open: The World of Closed-Eye Visuals

When your brain doesn't get enough stimulation, it will create its own! Colors you see before you fall asleep are a common but mild occurrence. In extreme classes of hallucinations, there are closed-eye visuals, caused by leaving your eyes closed for a long time; hypnagogia, which is caused by the onset of sleep; prisoners' cinema, which is caused by looking into a dark place for a long time; the ganzfeld effect, which is caused by blocking out all external stimuli; and Charles Bonnet Syndrome, caused by sight loss. Some of these can be whole imagined scenes or more abstract, fractal-like imagery.