In the past, for systems with a light, the light would stay on but dim a bit and "breathe" (slowly becoming brighter and then dimmer, at a similar speed as a person breathing in and out). I had sleep issues with my iMac so haven't used it for a few years; I'm trying with the Studio to get it to sleep and the monitor powers off and all, but the light doesn't seem to change. I'm not sure if sleep is functioning properly or not on my system; can anyone confirm if the lights are supposed to dim and possibly change brightness as described above?