After his father was rushed to the hospital with gastrointestinal bleeding, Yanatha Desouvre began to panic. So he did the one thing he knew would calm himself: He wrote.

“I’m so scared,” Mr. Desouvre started. “I don’t know what I’ll do if I lose my dad.”

In the next few weeks, Mr. Desouvre filled several notebooks, writing about his worry as well as his happy memories—the jokes he’d shared with his dad, the basketball games they’d watched, the time they put up hurricane shutters together, then cooled down with ice cream. Sometimes he cried as he wrote. Often he laughed.

“Writing allowed me to face my fear,” says Mr. Desouvre, a 42 year old who teaches marketing and business at a college in Miami. “My pen was a portal to process the pain.”

Something troubling you?

You should write about it.

An extensive body of research shows that people who write about a traumatic experience or difficult situation in a manner that psychologists refer to as “expressive writing”—recording their deepest thoughts and feelings—often show improved mental and physical health, says James Pennebaker, a psychology professor at the University of Texas at Austin. Dr. Pennebaker pioneered the scientific study of expressive writing as a coping mechanism to deal with trauma back in the 1980s.

Expressive writing is a specific technique, and it’s different from just writing in a journal. People need to reflect honestly and thoughtfully on a particular trauma or challenge, and do it in short sessions—15 to 20 minutes for a minimum of three days is a good place to start.

Dr. Pennebaker says that hundreds of studies over several decades have looked at the potential benefits of expressive writing, including for people with illnesses such as cancer, PTSD, depression, asthma and arthritis, and found that it can strengthen the immune system and may help lower the rate of colds or flu. Research also found the technique can help reduce chronic pain and inflammation. It may help lower symptoms of depression and PTSD. And it can improve mood, sleep and memory.

Now, a new website, part of a research endeavor called the Pandemic Project, gives people an opportunity to try expressive writing about the coronavirus. On the site, which was created by a research team led by Dr. Pennebaker, people are prompted to write about how the coronavirus is affecting them. A text analysis program then provides feedback. (This is not an expressive writing study, but the researchers will be analyzing the samples to look for themes around trauma and the coronavirus.)

Expressive writing works because it allows you to take a painful experience, identify it as a problem and make meaning out of it, experts say. Recognizing that something is bothering you is an important first step. Translating that experience into language forces you to organize your thoughts. And creating a narrative gives you a sense of control.

The mere act of labeling a feeling—of putting words to an emotion—can dampen the neural activity in the threat area of the brain and increase activity in the regulatory area, says Annette Stanton, chair of the department of psychology and professor of psychiatry and biobehavioral sciences at UCLA. Dr. Stanton’s research suggests that expressive writing can lead to lower depressive symptoms, greater positive mood and enhanced life appreciation. “Writing can increase someone’s acceptance of their experience, and acceptance is calming,” says Dr. Stanton.

Expressive writing can even help your relationships. A 2006 study in the journal Psychological Science found that when one partner wrote about his or her deepest thoughts and feelings about a romantic relationship, both partners began using more positive words when writing each other instant messages, and the couple stayed together longer. “We think expressive writing helps people work through struggles in a relationship, that leads to positivity, and that positivity elicits more positivity in return,” says Richard Slatcher, distinguished professor in the psychology department at the University of Georgia, who was the lead researcher on the study.

What if you hate to write? Don’t worry. You don’t have to put pen to paper. Researchers say that speaking your thoughts into a recorder works just as well. Try expressive writing for 15 to 20 minutes a day for a minimum of three days. Don’t worry about spelling or grammar or share your writing with anyone. But dig deep into your thoughts and feelings. The goal of the exercise is to find meaning in an event.