Here is the picture of the night light I have for my finches.  It is a 40 or 60 watt bulb in a cheap hanging aluminum light from Fleet and Farm.  There is a wide bar above the light (for birds that cannot balance well) and a rod below the light.  The bath bowl is in front, their food area is here too.  Because the rest of the cage has a lot of fake greenery, I cannot always see a sick, puffed up bird.  Instead, twice I have found a sick bird under the light and been able to isolate and treat them.
This area is below the "cage in cage", a cage built into the bigger cage, but separate.  I keep the obnoxious Zebra finches in the separate smaller cage, with them are two Tri colored Nuns.