This writing method was researched by Dr. James Pennebaker, a psychology professor. The research on this method is considered reliable, with over 200 peer-reviewed studies conducted.

For his research, Dr. Pennebaker invited college students to his laboratory for an experiment. He asked students to come for four consecutive days and write about their trauma for 15 to 30 minutes. Several months later, it was found that those who had expressed their deep emotions through expressive writing visited doctors 43% less frequently than the control group who wrote about mundane topics.

Additionally, according to neuroimaging research conducted at the Lieberman Lab at the University of California, Los Angeles (UCLA), repeatedly reflecting on and expressing experiences through expressive writing activates the prefrontal cortex. This is said to aid in memory reconstruction, improve emotional regulation abilities, and enhance self-understanding.