I occasionally fall asleep on the train on the way into work, and I’ve noticed an odd visual effect when I wake up.
People who are caucasian or asian appear bright yellow. Like, Simpsons yellow.
This lasts for about 30 seconds to 1 minute and eventually fades. I’m sure it’s caused by a combination of the fluorescent lighting and some sort of effect sleep has on vision, but my googling has only turned up links that suggest everyone in the train has jaundice, and I’m almost positive that’s not it.
Color oversaturation would be my guess. With your eyes closed, the lights shining through your eyelids would be red, and over the period of time you’re sleeping, the red cones in your eyes start getting ignored as meaningless noise. When you wake up, the red components of peoples skin tones would be subtracted by your brain as it tries to compensate for what was until seconds ago an environment saturated in deep red.
That is, however, just a guess. If someone else has the actual answer I’d be very interested in knowing.