Science Shows Something Surprising About Adults Who Still Keep Journals

When we think of diaries, we typically picture moody teens chronicling their social crises and unrequited crushes. But plenty of people continue to document their daily secrets long after high school — and according to recent science, they may have healthier brains than those who keep that information bottled up.

According to neuroscientists and psychologists, keeping personal information inside your head creates a conflict between two brain regions, which in turn leads to reduced cognitive function. The good news: The simple act of writing down those secrets may help undo the harm. In that way, keeping a journal has actual healing powers.

Why keeping your secrets is harmful

David Eagleman, a neuroscientist at Baylor College of Medicine, has developed one of the most widely known theories explaining how keeping secrets hurts the brain.

"The main thing known about secrets is that keeping them is unhealthy for the brain," writes Eagleman in his book Incognito: The Secret Lives of the Brain. "The reason a secret is experienced consciously is because it results from a rivalry."

According to Eagleman's theory, two brain regions are responsible for harboring a secret, and they become engaged in a "neural conflict." One region wants to get the information off your chest to relieve stress and the other wants to bury it deep into your subconscious. Ultimately, one region wins, but all that fighting wears your brain down. Mic reached out to Eagleman for greater detail regarding the exact neurobiology, but he declined to comment.

Other research can help explain what our brains endure as we try not to let our secrets out. According to Clayton Critcher, a psychologist at University of California, Berkeley, keeping secrets is one of our "self-regulation" processes, much like the one we go through when resisting junk food while on a diet. He believes these processes are so taxing that our brain can only handle one at a time.

In a study published in the Journal of Experimental Psychology earlier this year, Critcher and colleagues studied how expending energy to keep a secret reduced available cognitive capacity needed for other tasks. In a simulated exercise, the researchers found that those who concealed their sexual orientation during a simulated interview were subsequently physically weaker (based on grip strength) and less able to keep their cool during a frustrating social interaction than those who weren't forced to conceal their orientation.

"Constantly attending to what you’re about to say hurts other domains," Critcher told Mic, "and that can make it harder to control other emotional reactions. You're more likely to snap back at someone during a conversation."

The strain of secrecy manifests in symptoms of reduced mental and physical health. Keeping secrets leads to increased levels of the stress hormone cortisol. Research has shown that teenagers who keep secrets are more depressed and anxious, and that people who conceal information are more likely to develop headaches, nausea and back pain.

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How journaling can be an antidote

To relieve the burden that keeping a secret places on your brain, you need to get that secret off your chest. 

In his book and in interviews, Eagleman points to scads of research showing the benefits of telling secrets as a method of resolving the neural conflict within our brains.

“The act of telling a secret can itself be the solution," Eagleman writes in Incognito. "With someone you don't know, the neural conflict can be dissipated with none of the costs."

Of course, most of us aren't going up to random people and revealing our deepest secrets. That's where people who keep journals understand just how important they can be.

Research from James Pennebaker, a psychologist at the University of Texas at Austin, suggests that divulging a secret, even just by writing it down, may "unclog the brain" by increasing neural connectivity.

In one key study, he used electroencephalography, a neuroimaging tool that measures brain waves, to see how divulging a previously undisclosed trauma affects our brain. People who disclosed personal information exhibited more communication between the left and right hemispheres of the brain. Functional magnetic resonance imaging studies, Scientific American reported, have also shown that the brain lights up differently before and after writing about trauma.

Pennebaker's body of work has shown myriad benefits of writing about our secrets. Over the years, participants in Pennebaker's studies have exhibited decreased levels of stress hormones, improved immune system function, reduced increased T-cell count in AIDS patients and fewer stress-related visits to the doctor. The cathartic exercise has worked for people carrying around secrets both dramatic and somewhat mundane, like a job rejection.

Beyond improving our cognitive function, keeping a journal can may enhance working memory, improve management of stressful situations and reduce mistakes at work.

For the sake of our brains and bodies, the science shows that we need to declassify our secrets. People who keep journals seem to know the trick for doing so. And for those who don't, well, it may be time to pick up a Moleskine.

GE Scientists and Mic are partnering to share the latest advances in brain research and technology through BrainMic, a Spotlight Series that explores the universe in our heads, now through December 2014. Click here to read more from this series on BrainMic >>