Thanks for the feedback, all.
My wife is not at stage of going to docs, but we both realise if it persists or gets worse, then a visit is needed. I was aware of that manoeuvre, nikki, it was in some book I read recently. ("Adventures in being Human" is a great book, highly recommended.)
Its the light and headache bit that is more alarming to me, but I know dizziness and all symptoms can be really debilitating. So far just watching closely/waiting. (I don't think its impacted wax, her hearing is no affected.