Refs for Blue light is not more effective or efficient than white light

Age-Related Changes in Acute and Phase-Advancing Responses to Monochromatic Light. Journal of Biological Rhythms, Vol. 24, No. 1, 73-84 (2009)
Sletten TL, Revell VL, Middleton B, Lederle KA, Skene DJ.

"Reduced sensitivity to short-wavelength (blue) light with age has been shown for light-induced melatonin suppression. The current research aimed to determine if a similar age-related reduction occurs in subjective alertness, mood, and circadian phase-advancing responses."

"Following blue light exposure, responses in older men were significantly diminished compared with young men for subjective alertness (p < 0.0001), sleepiness (p < 0.0001), and mood (p < 0.05) during and after light exposure. There was no significant effect of age on these parameters following green light exposure. The phase advances to both blue and green light were larger in the young than older subjects, but did not reach statistical significance. ... The current results add to previous findings demonstrating reduced responsiveness to the acute effects of blue light in older people (melatonin suppression, alertness)." Abstract

Light-Induced Melatonin Suppression: Age-Related Reduction in Response to Short Wavelength Light. Experimental Gerontology. 2005 Mar;40(3):237-42
Herljevic M, Middleton B, Thapan K, Skene DJ.

"Age-related changes in lens density are known to reduce the transmission of short wavelength light, ... Melatonin suppression was compared across light treatments and between age groups. Significantly reduced melatonin suppression was noted in the elderly subjects following exposure to short wavelength (456 nm) light compared to the young subjects. These results are likely to reflect age-related changes in lens density." Abstract