Yes, I believe that Earth hour does help the environment. This id due to the fact that it raises awareness for environmental issues that exist and if people are ignorant of these issues, how can they help to stop it? This is why Earth Hour helps. I rest my case.
Yes, Earth Hour helps the environment in that it raises awareness about environmental issues. If a populace remains ignorant of environmental issues, no progress can be made in the first place. One may argue that Earth Hour itself does nothing at all, and this is true, but it is missing the point of raising awareness.
"Earth Hour" is something middle class liberals who want to do something symbolic but not actually change the underlying problems regarding the issue at hand, as they would require a fundamental shift in their lifestyles. It does not do anything, it does not even send a message to others, it is simply a way for you to do something to make you feel good about your impact on the environment.