The author of 'Jay's Journal' is Beatrice Sparks, who presented herself as the editor rather than the actual writer. She claimed the book was based on the real diary of a teenage boy named Jay, who supposedly descended into drug use and occult practices before committing suicide. Sparks is known for her 'found diary' style, similar to her other works like 'Go Ask Alice.' Critics have debated how much of the content is authentic versus fabricated for dramatic effect, but regardless, the book became influential in young adult literature about addiction and mental health. Sparks specialized in cautionary tales framed as real accounts.