I have a full spectrum light by the cages for my birds. Wednesday litterally basks in it, she will move to the point closest to the light and its just like she is sitting enjoying the sunlight.
I am not sure i have noticed any benifit since getting the lamp, but in winter around here there is so little daylight and natural sun, and it is too cold to take them out 3 seasons of the year...so fake sunlight seems like the least that i can do.