Flash Contest #2 || Riddles Challenge || 20/04/2021

Hello everyone, so I'm new here and I found my way to this wonderful community. And what better way to kick off my arrival than with a riddle contest?

Okay, here goes...

RIDDLE:
So I went on a visit to my Grandma's, I was to spend the night there. Due to traffic, I got there a bit late and when I did I saw a young cousin i had never met before. She was reading a book, focused and touching each word as she mumbled the words to herself.

Soon, power was interrupted and the house was plunged into darkness. But this my cousin was still reading. I knew because I could still hear her muttering under her breath. She had no lamp, there was no light from outside, the room was so dark I couldn't see my hand in front of my face. But she kept on reading. How?

So here it is.
If the post remains without an answer, I will supply it.

Thank you @belenguerra, @fendit and @writingnreviews for this opportunity.