in actual fact i don't use this colour, but use the lighter blue as per the background in the next section below !
it is well worthwhile to understand colour (english spelling!) wheels which can be fun !
a hue and saturation colour chart
white (#FFFFFF) naturally contains blue (#0000FF) !
“cool” i.e. whiter (6000ºK and above) fluorescent lights have much more blue in compared to “warm” (4000ºK and below)
overcast days have a surprisingly high colour temperature of about 6500ºK
halogens have a slightly higher colour temperature of 3000ºK compared to the standard incandescent bulb at 2700ºK
this would seem to give maximum energies in the useful pRGC stimulating wavelengths without any unnecessary reds
the pRGC are retinal cells in the eye that set the circadian clock
of course red can be used the other way, to simulate being in darkness !