Scientists in Dresden are investigating the influence light has on health. Light controls circadian rhythms and the timing of metabolic processes. This becomes particularly apparent in reference to sleep.
Blue light, by contrast, keeps people awake and stimulates activity. Researchers are now also probing the mechanisms behind this and how blue light influences the eye. So far they've discovered that the human retina is particularly sensitive to blue light at certain times of day, and that the eye can actually be damaged by exposure to it, and the aging process accelerated. They're using this information to evaluate energy-saving light bulbs. LEDS are energy efficient, but the light they generate contains a larger proportion of blue. That's led scientists to say it could be causing sleep disorders.