The article as a whole is quite good though you seem to be informed as to how the circadian rhythm works. It is an independent system from it's environment, meaning it relies upon itself to keep it on track and on time. The natural light will slow the production of melatonin significantly but will not affect our circadian rhythm. A study was conducted by a German scientist in the 80's (I could be off on the date) in which he stayed in a room with no natural light for two months. He informed other scientists when he ate and slept by telephone. He stayed true to his 24.25 hour circadian rhythm even with no natural light. That being said, your article is still quite nice and it was nice to hear all the benefits of working near natural light.