In an abstract presented at last year’s SLEEP 2010, the 24th annual meeting of the Associated Professional Sleep Societies LLC, scientists showed that color perception is altered while a person is awake, and reset during sleep.
From the abstract:
On a given trial, a full-field homogeneous stimulus of either slightly reddish or greenish hue was displayed. The observer had to judge if the stimulus was greener or redder than their internal percept of neutral gray.
[I]t is not sleep that causes gray to be classified as red- dish, but prior wakefulness that causes gray to be classified as greenish and sleep restores perception to achromatic “equilibrium”, i.e. following overnight sleep, physical gray is perceived as gray.
I find this fascinating, that being awake can change how we perceive color.
The SLEEP 2010 abstract supplement is available for download on the website of the journal Sleep at http://www.journalsleep.org/ViewAbstractSupplement.aspx (as a PDF) and you will find this abstract on page 40 of the PDF (it is abstract #0106 on abstract page A39).