What they did is they compared the light of LEDs and HID to that of sodium lamps, mostly found in outdoor lighting (for those who don't RTFA). The blue light, which is missing in the sodium spectrum, supresses the melatonin production. The same process happens every morning when you get up and turn on the light or go outside. As sodium lamps are mostly used in streetlighting etc. I think this is actually a benefit instead of being dangerous. Supressing the melatonin fights the fatigue which might prevent some car accidents, although I'm not sure if this effect is high enough for this.