Speak Screen halts when Auto Lock comes on

If I am using Speak Screen to have a book read to me from Kindle, and Auto Lock comes on, Speak Screen stops reading.

I have friends who use this same functionality who say their phone keeps reading to them when their phone is locked. Does anyone know what setting I should use to do this? If I set Auto Lock to "Never" it keeps reading, but then my battery drains quickly because the screen stays on.

Thanks!