There’s a treatment that’s been shown to be effective for improving blood pressure, insomnia, overall well-being, and chronic pain. It’s free, easily accessible, and doesn’t require breaking a sweat or even leaving your couch. What is this treatment? Expressive writing.

Expressive writing is writing that’s self-reflective, deeply personal, and emotional. While there are now thousands of published studies on the benefits of expressive writing, two landmark studies merit closer attention.

Back in 1986, the social psychologist and writing therapy pioneer James Pennebaker and his colleague Sandra Beall randomly assigned college students to come in to their lab at Southern Methodist University and write about either traumatic or trivial events for four consecutive days. In the following months, those who wrote about traumatic events went to student health services for illness at about half the rate of the control group, and showed better immune functioning.

The second study tested expressive writing in an entirely different population: recently unemployed professionals (mostly male engineers) who had worked for their employer an average of 20 years before losing their jobs in a large corporate layoff. Stefanie P. Spera, Eric D. Buhrfeind, and Pennebaker assigned participants to expressive writing about their job loss, or writing about something unrelated, or no writing at all.

Eight months later, a little more than half of those in the expressive writing group had accepted new full-time jobs, in contrast to only 24% and 14% of those in the writing-control and nonwriting groups, respectively. In fact, the effect of expressive writing was so robust, the researchers terminated the study early and offered the expressive writing intervention to all the participants.

How does expressive writing work?

There are various theories on what exactly makes expressive writing work, but one important feature seems to be that such writing helps us “process” our thoughts and feelings more deeply. That allows us to make new realizations. There’s an old saying in psychology: “What you resist, persists.” By looking at our experience through “new glasses,” expressive writing can help us get “unstuck.”

What should I write about?

Write about something that’s bothering you. It could be an event that happened recently, or in the past, or an issue you’ve been avoiding, for days, weeks, or years. This could be a difficult relationship, work situation, or health issue. Anything you might feel “stuck” about. Stick to a single topic at each writing session; feel free to change topics at the next one if you like. Find a time when you can focus without interruption for a few moments, and be as open and honest as you can with yourself.

How do I do it?

Once you start writing, keep going without interruption for 15-20 minutes. If you run out of things to write about, it’s OK to repeat yourself. Disregard punctuation, grammar, style, and your own inner critic. Commit to writing for four consecutive days.

If you find you don’t know exactly how you’re feeling, review what some psychologists consider the five core emotions — happy, angry, sad, afraid, ashamed — and notice which ones resonate. If you still feel stuck, try writing with your nondominant hand or in the third-person. If you feel sad immediately after your writing session, it’s typically a transient emotion and not an indicator that expressive writing isn’t for you.

You don’t need a special journal. Scribble on the back of an envelope, scrap paper, or type on a computer if you prefer. If you’re unable to write, speak for 15-20 minutes instead and record it.

What do I do with my writing when I’m done?

No need to save what you’ve done if you don’t want to. Delete it, tear it up, shred it, or have a ceremonial burning; it’s up to you.

Could expressive writing ever be detrimental?

Expressive writing is not recommended immediately after a traumatic event. There’s little evidence that it’s helpful at that point, and based on research on a related cognitive processing intervention (Critical Incident Stress Debriefing), it may even be detrimental.

But if expressive writing ever feels unbearable, stop. If you try expressive writing for a few days and it feels like it’s making things worse, let it go for a while.

Finally, expressive writing is not a first-line treatment for severe major depression, particularly with suicidality. If you are having suicidal thoughts, there’s help available: Call the U.S. National Suicide Prevention Lifeline, 800-273-TALK (8255) or text HOME to the Crisis Text Line at 741741.

Stacey Cahn is a clinical psychologist and assistant director of integrated health at Rowan University. She will address the issue of writing for good health further at The Inquirer’s “Telling Your Health Story” event on Sept. 28. For tickets: inquirer.com/healthstory.