Remember that your character doesn't know that she even
has sanity points to begin with. She may have a rough awareness of an equivalent of hit points (immediate physical well being), but usually she isn't thinking about her sanity and the fact that she is slowly losing it. In character, she very likely isn't even aware that her sanity is slipping away from her.
If you're from a 'narrativist' background, think about the Sanity mechanic like a narrativist. Characters aren't likely losing Sanity from "glancing at the wrong book," but by reading the disturbed writings of others and themselves being in turn disturbed by them. They have read and collated the contents. Consider the following quote from H.P. Lovecraft's Call of Cthulhu:
quote:
The most merciful thing in the world, I think, is the inability of the human mind to correlate all its contents. We live on a placid island of ignorance in the midst of black seas of infinity, and it was not meant that we should voyage far. The sciences, each straining in its own direction, have hitherto harmed us little; but some day the piecing together of dissociated knowledge will open up such terrifying vistas of reality, and of our frightful position therein, that we shall either go mad from the revelation or flee from the deadly light into the peace and safety of a new dark age.
To me, this explains why the character is losing sanity best. It's not 'glancing at a book.' It is the piecing together of forbidden, disturbing, and terrifying knowledge, while the rest of the world continues to turn in ignorance of this as it did before. While everyone else think it's just another day, your character has consumed a piece of knowledge that she legitimately believes, and that terrifies her.
I think that's a much better way to read a Sanity Loss than "Whoop! Lost 3d6 SAN!" As a GM when I'm performing at my best, I'd do my best to try to explain that in context to the players - not only that their characters lost Sanity, but the
why of it.