if she has specific environmental requirements for that, it's relevant information she needed to provide to someone thinking of moving in with her.

Oh yeah, I agree, although I wouldn't be surprised if she thought she had - no/minimal overhead lighting seems to have solved it when she was at LW's place before they moved in together, and she might not have thought to bring up the lightbulbs. But either way I was more reacting to him seeming sceptical that she even has migraines, given that she's apparently put effort into avoiding triggers.