I used to leave all my electronics charging overnight. Then I read an article on phantom energy use (you know, when devices draw power even when off). So I started unplugging them before going to bed. The room got darker and quieter, which helped me fall asleep quicker. Now I sleep more soundly and save a little electricity too.
Honestly though, how much power are we really talking about here? I get the idea of phantom load, but my whole coffee maker or phone charger probably uses less power overnight than my AC does in five minutes. It feels like we're focusing on pennies while ignoring the dollars. If the darker, quieter room helps you sleep, that's a great bonus. But I'm not convinced the energy saving alone is that big a deal for most people.