AIP ENR 1.5 Para 1.7
Note 3
The circling area is determined by drawing an arc centred on the threshold of each usable runway and joining these arcs by tangents.
Repeat of Manymak's quote, just with AIP ref.
Comes down to whether an unlit runway is useable at night.
No argument that the circling minimum covers the area of all runways, but again, if you are conducting a visual maneouvre (which circling is), how can you be visual with an unlit feature at night?