There is a lot of buzz about it, but what you really want is a window.
When the sun rises in the morning, the light has to travel diagonally through the atmosphere. The longer the distance it travels, the redder it gets as the shorter wavelength blue light gets gets blocked. At noon, when the sun is highest, the most blue light gets through. Then as the day goes on, the light gets redder again as the sun gets lower.
Our bodies have an internal clock that is tuned to these changes in light – the circadian rhythm. For a long time nobody worried much about it, particularly architects and lighting designers. They couldn't do much about it either, because electric lighting was wither on or off, and you couldn't change the color.
© Nobel Committee
