Mariana Figueiro, PhD., who heads the LRC’s light and health program explains:
“Within the mechanism that affects the circadian system are two color opponent channels. One of those is the blue vs. yellow (BY) channel, which seems to participate in converting light into neural signals to the part of the brain that generates and regulates circadian rhythms.”
A person attuned to the changing colors of outdoor light will notice that just after the orange-colored sun sets, the world is bathed in blue light from the twilight sky. So perhaps it’s not surprising that our body rhythms are tuned by this color.
In one LRC study, patients with Alzheimer’s disease experienced more hours of sleep per night after being exposed to blue LED lights than they did after being exposed to red lights.
“Blue sky is ideal for stimulating the circadian system because it’s the right color and intensity, and it’s ‘on’ at the correct time for the right duration—the entire day,” said LRC director Mark Rea, Ph.D.,
Presumably, since non-human animals also have the BY channel, they would respond to the same signals.
Science Daily article about waking up teens with colored light
RPI Lighting Research Center article
Painting is called "Bonfire" by Isaac Levitan