Clinical Management of Delayed Sleep Phase Disorder
Behavioral Sleep Medicine 2007, Vol. 5, No. 1, Pages 57-76.
L. Lack. H. Wright
"It should be noted that broad-spectrum white light, traditionally used for bright light therapy, also contains blue light of potential concern particularly for very high intensity, long-duration exposure. Clearly, the safety of bright light therapy for people needs investigating. In the meantime it would be suggested that light in the 500 to 530 nm wavelength range (blue–green) should still be effective while avoiding the putative blue hazard."
Impact of blue vs red light on retinal response of patients with seasonal
affective disorder and healthy controls.
Progress in Neuropsychopharmacological and Biological Psychiatry 2011; 35(1):227-31.
Anne-Marie Gagné, Frédéric Lévesque, Philippe Gagné, Marc Hébert.
"The main finding of this experiment is that blue light reduces photoreceptor responses after only a single administration. This brings important concerns with regard to blue-enriched light therapy lamps used to treat SAD symptoms and other disorders. Full Paper
Retinal Photodamage by Endogenous and Xenobiotic Agents.
Photochemistry and Photobiology. 2012. 88(6):1320-1345
Wielgus AR,and Roberts JE.
"Intense visible light sources that do not filter short blue visible light used for phototherapy of circadian imbalance (i.e. Seasonal Affective Disorder) increase the risk for age-related light damage to the retina...This article will review the underlying reasons why visible light in general and short blue visible light in particular dramatically raises the risk of photodamage to the human retina." Full Paper
Note: more recent references on the risk of eye damage from light therapy can be found in the section marked - For Therapists