For all you know, a witch might be living next door to you right now. (1.24)
The Witches is written in the second person only for a short portion. When it is, though, our narrator really tries to instill some fear into us. He wants us to be just as afraid as he was, so that we can better understand his story.
"A witch wouldn't come in through my window in the night, would she?" I asked, quaking a little. (2.71)
When you're afraid, suddenly the most mundane, day-to-day activities (like sleeping!) seem scary. What other daily activities seem frightening to our narrator as he learns about witches?
I froze all over. (4.68)
Fear can really affect us physically, not just mentally.