Beth
It is scary when that feeling comes over us. It's like panic, anxiety and fear all rolled into one thing. Hypervigelance is the right term for that feeling we think.

Some of twilight's ideas are good ones and help with grounding. I here you twilight when you say reading requires too much concentration sometimes and that even "good" sounds can be scary. For that reason we have made a "good feeling" book. It's just cut out serene pictures pasted on plain paper and made into a "book". No words. Just a picture book of things we like.
It helps to ground us.