Over the past couple of years I've had this strange phenomenon that occurs sometimes. If I'm laying in bed, going to sleep, and I happen to be somewhat in that "not yet asleep, but still not awake" phase and, let's say the circuit breaker (which is just next to my bed) clicks on and makes this loud buzz sound for just a second, this strange black-and-white visual shoots across my vision. It looks like this square spiral pattern of black and white, and it appears only for a second (often times pulsating very rapidly with the sound of the buzz) and then I jolt awake.

Perhaps others have had this experience? What is it?