Re: Help me to understand someone else's idiosyncrasies........
I wear ball caps when I need more sun protection and/or the ease of not having to worry about what my hair looks like. Plenty of women wear ball caps indoors, day or night. That wouldn't even register as odd to me, honestly.
The sunglasses indoors is a little less common. As others have posited, though, there are a myriad of reasons why someone might. My SO routinely wears his sunglasses indoors if his usually sensitive light blue eyes are already tired and the overhead lighting or some source of glare is particularly bothersome. I once wore mine to class for several days while my eye healed from a busted blood vessel. Not only was my eye particularly sensitive, but the white being fully blood red was also attention-grabbing in a way that made me uncomfortable.
You'll find that many of the truths we cling to depend greatly upon our own point of view. - Obi Wan Kenobi