As a child, after 2 minutes of turning on and off a light, I distinctly remember having been told by my mother, that it takes more energy to turn on a light bulb, that it does to run it for 30 minutes. Terrified of the environmental ramifications I never did that again. However I'm wondering if it is true for a standard old light bulb. I seriously doubt it. However what about a halogen, florescent, or even LED? Any thoughts?