Reading from a book each night before bed according to Jang encourages the brain to remember the text

Which of the following reflects the proper punctuation of the above sentence?

Reading from a book each night before bed, “according to Jang,” encourages the brain to remember the text.
“Reading from a book each night before bed,” according to Jang, “encourages the brain to remember the text.” . . .
[R]eading from a book each night before bed according to Jang encourages the brain to remember the text?
“Reading from a book each night before bed (according to Jang) encourages the brain to remember the text”.