Hypnagogic Light
Light on closed eyelids, and what the visual system does with it.
Controlled flickering and continuous light viewed with the eyes closed can produce vivid internally perceived colors, patterns and imagery for some people. The light is not a picture. What is perceived is generated by the visual system responding to the stimulation.
Flickering light is not appropriate for everyone and requires screening. Availability of any specific system through Other Way In is not yet confirmed.