Initial experiments with covering the LED display of numbers on the clock radio beside the bed are resulting in more movement while sleeping, a shorter period of time falling asleep, more vivid dream recall.
I am wondering if this is like eliminating the distraction that a television, even a silent one, can cause if left on in a room where people are not actually watching but keep glancing at it.
Also, the fact that we can have our eyes closed but open or close our 'vision' behind those closed lids may be a factor. Nictitating membrane comes to mind; maybe the 'memory' of one.