Changing light levels somehow seems very troublesome in dreams. Usually, when a light level in a dream is set, it does not change untill it has an opportunity to do in a radical fashion (i.e. total scene switch). Dreams seem to avoid changing light levels in dreams in view of the dreamer, for some reason. I personally have had a lucid where everything was getting darker, but for the darkening to occur my dream used all sorts of tricks to obstruct my vision of the light. For example, I was looking at a window from which light came, and the light level remained the same throughout. Then suddenly a door closed between me and the window, and when I opened it again the window was a whole lot darker.
I don't know why adjusting light levels is a problem, so I'm not sure what it means that you can. Maybe you can describe in more detail what happened? I'm pretty sure it couldn't have gone like in real life.