I wonder if that might be part of the problem... I mean, it getting dimmer so early, thus increasing the dark places. It may be beneficial to him to get some artificial lighting to make up for the dimness of the room.
I'm suggesting this, as Tomi Girl came to me from a dimly lit home. They had blankets or sheets covering the windows and kept most of the house dark, unless they had a light on. Even with the light, the quality of the light wasn't that great. On top of that, they ended up covering her up 24/7 because she was "too noisy". While there, she became a chronic egg layer. I can safely say right now that I do not have any chronic egg layers! The house I used to live in had an east and south facing windows, and surprisingly got pretty good lighting throughout the day! House I'm in now, the birds room only has one window and it faces north, so lighting isn't as great as I would like it to be, and have been considering getting artificial lighting. Knock on wood though, no crazy egg laying!
So my thought process is, if it's too dim, perhaps increasing the quality of the light that he gets during the day may help to kick him out of it.