I never thought about it but the best appointments with T were at her house and the only lights we the natural lights. I always felt more relaxed at her home office (though only was there a couple of years), I always attributed it to her dog being there, having to hear anybody in the hallway, and she seemed more relaxed in her home. I do remember though the times we didnt need lights very fondly. Maybe I should mention it to EMDR T.