There's Science Behind the Secrets We Humans Keep

image of two people sharing secret over double exposure cityscape
Sharing and keeping secrets can have a measurable impact on the human body and psyche alike. Jasper James/Getty Images

Have you ever been asked to keep a secret? Or confided in someone, only to beg them not to tell? You're not alone. According to research, the average person in the United States has 13 secrets, five of which are still completely secret, shared with no one. And there's a 60 percent chance that one of the secrets is about money, say researchers at Columbia University.

As hosts Robert Lamb and Joe McCormick explore in this Stuff to Blow Your Mind podcast episode, secrets are not only common, but carry a weight of their own that can have mental and physical consequences.


At its most basic, a secret is something kept from knowledge or view, but that scenario can encompass a lot of things — an old high school softball trophy stored in your closet, for instance — that aren't intended to be surreptitious. For the purpose of his research on secret-keeping, Michael Slepian, a professor of management at Columbia Business School, defined secrecy as "an intention to conceal information from one or more individuals." That encompasses a greater range of real-life situations.

Defining secrecy is only one part of the equation. More to the point is the deleterious effect that secrets can have on the body. Holding a secret in one's mind can prompt physical changes, including continual waves of stress hormones that can lead to everything from high blood pressure and gastrointestinal problems to weakened immunity and memory loss.

And that's where the "chicken and egg" dilemma comes in. While it's entirely possible that keeping secrets make people physically sick, it's also possible that the people who are more likely to keep secrets are predisposed to these illnesses. In fact, that's precisely what Anita Kelly, a psychology professor at Notre Dame, discovered after studying 86 undergraduates for secret-keeping research that was later published in the Journal of Personality. The findings challenged "conventional wisdom about the dangers of keeping a major secret and suggest that, instead, the kind of person who is secretive simply might be more vulnerable to symptoms," wrote Kelly.

girl whispering to woman
What is the likelihood a person will keep silent on something told to them in confidence?
Tang Ming Tung/Getty Images

Keeping a secret can be bad for your emotional health, too. The brain's orbital prefontal cortex is hardwired to tell the truth, but when hiding the truth, it compensates by putting additional pressure on the cingulate cortex. This, in turn, leads to anxiety, fear and greater production of stress hormones.

Another study by Kelly, co-authored with Robert Rodriguez and published in 2006 in the Journal of Social and Clinical Psychology researched the effects on health when students wrote down confessions of personal secrets while imagining one of three different conditions — an accepting recipient, a non-accepting recipient or no confidant at all. The study found those who wrote their confessions to an "accepting" confidant had fewer illnesses after eight weeks than those who wrote to a "non-accepting" person, which points to a crucial mind/body health link.

The idea that writing down a secret can lead to a positive effect on health, new insights and closure stems from the Zeigarnik Effect, named after the psychologist who identified the phenomenon in the 1920s. The Zeigarnik Effect describes people's generalized ability to remember uncompleted or interrupted tasks better than those that are completed. Thus, people will experience automatic and intrusive thoughts about a secret. The act of writing it down can calm those thoughts — even if you are only sharing the secret with yourself.