Unforseen events in my heroine's life

I can't believe how long it took me to realise that the blindingly painful headaches I have been experiencing of late are a result of my over-bright computer screen. All it took was for me to change a few minor settings, and I am as right as rain.

This got me thinking. If there are things in my life that are directly affecting my comfort and well-being; these things which I am ignorant of, surely my characters would have similar experiences.

As I have been developing my character profiles, I became aware of the fact that I know things about my heroine that she doesn't know about herself. So will she act in a certain way due to an invisible factor, or am I just thinking that she would? If so, would the actions of the heroine confuse the reader?

So much to ponder! Am I over thinking this? Should I just let my character act for herself? I would love to hear your thoughts on this!