A study on mice indicates that color signals reaching the eyes are "stored" in the suprachiasmatic nucleus in the brain. It was thought only sunlight was responsible for setting the body clock. This has been brought into question, however. The research controlled the brightness of artificial sky and also added color blended into the level of brightness.
With only dawn sunlight in the test room mice seemed confused and their body temperatures lagged behind the norm by 30 minutes. When orange and blue was added to the dawn light the mice were perfectly normal in behavior and temperature.
It seems the light/color information is stored in suprachiasmic neurons in a special way. Biopsies show a time lag in the firing of these neurons which ties into low body temperatures. Mammals have evolved in tune with this planet. The animal to Earth "bonding" seems to be very close indeed.
✴ Biology by Ty Buchanan ✴