Overdriving lights etc

[Rikko]

I'm sure Steve will jump in here before long, but IMO it can't change the spectrum. The spectrum of the bulb is determined by the coating inside the bulb - the invisible UV produced inside the bulb is "transformed" when it collides with whatever composition sits on the inside surface of the bulb. If a bulb is bring driven harder, there should just be "more" light colliding with the bulb coating, but no real change in its physical properties.