Eigengrau

Eigengrau (German: "intrinsic gray" / literally: "own gray"), also called Eigenlicht ("intrinsic light"), dark light, or brain gray, is the uniform dark gray background that many people report seeing in the absence of light. The term dates back to the nineteenth century, but has rarely been used in recent scientific publications. Nowadays the phenomenon is more commonly referred to as "visual noise" or "background adaptation".