IN THE BLUE CORNER

摘要

Blue light: is it good or is it bad? On one hand it is meant to be good for you, keeping you active and alert during the day, on the other there are reports that it can damage your eyes and keep you up at night. Well, the answer is all to do with the human physiology and how our body responds to light within the range of 400-500 nanometres (nm), or the blue range of the visible spectrum. ORCADIAN RHYTHM As we now know, our eyes have three types of photoreceptors: cones (around 6m), rods (around 120m) and photosensitive retinal ganglion cells. Cones deal with high-definition daytime vision while your rods are for the nighttime. The more recently discovered photosensitive retinal ganglion cells do not actually contribute to vision at all. As was determined at the beginning of this century, they are used to tell our body what time of day it is.