Generally, the only people who need to be concerned are those with serious pre-existing eye conditions. To be safe, always consult with your physician prior to using light therapy for medical or mental health purposes. The nice thing about light therapy is that the side effects are experienced by only a small percentage of people, and typically are temporary. They can include a jittery feeling, excitability, mild nausea, and mild burning of the eyes. For the majority of people afflicted with seasonal affective disorder and its related disorders, the answer is no.
Medical research indicates the therapeutic effect comes from the high intensity of light.
This high intensity, generally ten to twenty times brighter than regular room light, stimulates the brain to produce the chemical changes responsible for the antidepressant effect of light. One should be careful about the light being too bright. As can be seen in the diagrams, these specialized lights, made by Excella, are the next best thing to sunlight. In summary, replacing the light bulbs in your house with full spectrum lighting will help make your house look great, but typically is not useful for producing true therapeutic effect. Some insurance carriers will reimburse.