I was just thinking about posting a question about this the other day... When i close my eyes, most of the time i see an 'X' that covers my entire field of view, that is to say the four lines reach (beyond?) the edge of my vision. The lines themselves seemingly have no 'substance' i.e. they are strictly open line segments intersecting at the centre of the field of view. They look 'electric' and are surrounded by a fuzzy cloud as if the lines were 'buzzing'. With a little effort, the 'X' can be divided by the addition of a vertical and horizontal line to make eight segmented areas - with yet more effort, the visual field can be divided once again into 16 and so on ( i assume ? ) . Sharing experience with some of the previous comments, there appear to be vortices about 1.5 cm wide slowly cruising around. The next time you're a passenger in a car/bus with the sun on your side and riding past 'scantily' trees, close your eyes and let the sun shine on you while the trees cast shadows over your face, alternatively, lay under a bright ceiling spotlight and wave your hands past your eyes as fast as you can - voilĂ♥, your own personal kaleidoscope. There is a fascinating article on the 'Neurobiology of [an] hallucination' for those who are keen (don't be dismayed by the title; hallucination is a purely scientific term) - and an even more fascinating comment (fourth one down) for the very keen. I'm aware that i cannot post links? So, google 'closed eyes hallucination + neurobiology' and click the first link. I haven't offered any explanations, I'm just answering the initial question is all that's my two cents