Vitalite useable life?

Someone just told me about a post they read awhile back about these lights.
 I don't think the post was here.  Anyway, I guess the post said that a vet
told someone that Viatlights lose their full spectrum capacity after 30 days.
 I guess a study was done on these and that's what they found.  If this is
true, I wonder how many other lights lose their capabilities in a short time?
 This is something that now has me deeply concerned!  Jeff