Yes, it’s covering a window that faces the street, it took that to block out the bright 1000 watts from outside view.
I know a white reflective board or foil would reflect light more, but it’s a room that’s also used for other things, the light is pretty bright as it is in the room.
The light will be controlled by a timer and the room’s door will be shut while the room is dark and won’t be disturbed.