Circadian math: 1 plus 1 doesn't always equal 2

Saturday, June 7, 2008 - 15:49 in Biology & Nature

Researchers have found that the circadian system may be able to distinguish between lights of different colors. Like a wristwatch that needs to be wound daily for accurate time-telling, the human circadian system — the biological cycles that repeat approximately every 24 hours — requires daily light exposure to the eye's retina to remain synchronized with the solar day. In a new study published in the June issue of Neuroscience Letters, researchers have demonstrated that when it comes to the circadian system, not all light exposure is created equal.