Phosphenes

What is the name of those things you see, when you close your eyes? I think it's phosphenes. The reddish patterns. The little strikes and dots and blurry little lines you see floating around when you close your eyes. And no-one really knows what they are, or what they're for. Sometimes they seem to be brought on by sound. Or random electrical or magnetic firing. Sometimes phosphenes are called 'prisoner's cinema'. Some kind of eternal, plotless, avant-garde, animated movie. Or maybe they're just screensavers. Holding patterns that just sit there. So your brain won't fall asleep