Their should be a signal intensity level high enough to be distinguishable from nothing but still low enough to cause slight annoyance rather than traumatic agony over a short period.
Overillumination has been known for some time to cause various other deleterious health effects anyway, and flicker aside fluorescents just put out plain terrible light. It completely baffles me why so many establishments install it (well, workplaces; retailers like it because it makes you buy more apparently).