Wednesday, June 9, 2010
Sleep researchers have observed a strange phenomenon that occurs the longer we stay awake. Over the course of the day the color gray starts to appear greenish. Sleep reverses the effect and the next morning gray looks like gray again.
It appears color perception drifts over the course of a day and is restored during sleep.
The study presented this morning at SLEEP 2010 is one of the first ever to investigate the effects of sleep on color perception.
A small number of participants viewed a variety of gray pictures with either slightly reddish or greenish hues. Before and after sleep, each judged whether the color was more red or green than plain gray.
Researchers noticed colorless items were classified as greenish, except after sleep. The effect was the same for both eyes.
Further testing found that overnight, full-field monocular stimulation with a flickering red “ganzfeld” did not negate the sleep-induced effect. The authors suggest the color perception resetting is an internal process largely unaffected by external visual stimulation.
Further research is needed to determine why color perception drifts and is restored by sleep.