An innovative research has demonstrated that sleep corrects the drift in color perception that occurs during restlessness.
Results point out that prior sleeplessness caused the color gray to be classified as having a vaguely but considerably greenish tint. During night sleep restored perception to achromatic balance so that gray was perceived as gray.

Main researcher and lead author Bhavin Sheth, assistant professor of electrical and computer engineering at the University of Houston in Texas mentioned that in accordance with the authors, scientists had not previously investigated how sleep might influence the way we look at the world that surrounds us. This is among the first researches to examine the results of sleep on perception. Also he declared that their findings put forward that sleeplessness causes color classification to drift away from neutrality, and sleep restores color classification to neutral. The study implicated five people who viewed a full-field, homogenous stimulus of both slightly reddish or greenish type and the observers had to judge whether the stimulus was greener or redder than their internal perception of neutral gray.

Across trials the hue was wide-ranging. One pair of monocular tests was performed just before members went to sleep, and testing was repeated after participants slept for an average of 7.7 hours. Additional testing found that while sleeping, full-field monocular stimulation with a sparkling red ‘ganzfeld’ failed to nullify the resetting, sleep-induced effect. An achromatic stimulus was still less likely to be classified as greenish following sleep, with no statistical dissimilarity in the scale of the resetting in every eye.

According to the authors, this suggests that color resetting is an internal procedure that is mainly unchanged by external monochromatic visual stimulation.

The research was offered in San Antonio, Texas, at SLEEP 2010, the 24th yearly assembly of the Associated Professional Sleep Societies LLC.