People are horrible at keeping secrets. As in, really, really bad at it (no matter what anyone may tell you to the contrary). And you know what? We’re right to be. Just like the two Rhesus Macaques in the picture above, we have an urge to spill the beans when we know we shouldn’t—and that urge is a remarkably healthy one. Resist it, and you may find yourself in worse shape than you’d bargained for. And the secreter the secret, the worse the backlash on your psyche will likely be.

I never much cared for Nathaniel Hawthorne. I first dreaded him when my older sister came home with a miserable face and a 100-pound version of The House of the Seven Gables. I felt my anxiety mount when she declared the same hefty tome unreadable and said she would rather fail the test than finish the slog. And I had a near panic attack when I, now in high school myself, was handed my own first copy of the dreaded Mr. H.

Now, I’ve never been one to judge books by size. I read War and Peace cover to cover long before Hawthorne crossed my path and finished A Tale of Two Cities (in that same high school classroom) in no time flat. But it was something about him that just didn’t sit right. With trepidation bordering on the kind of dread I’d only ever felt when staring down a snake that I had mistaken for a tree branch, I flipped open the cover.

Luckily for me, what I found sitting on my desk in tenth grade was not my sister’s old nemesis but The Scarlet Letter. And you know what? I survived. It’s not that the book became a favorite. It didn’t. And it’s not that I began to judge Hawthorne less harshly. After trying my hand at Seven Gables—I just couldn’t stay away, could I; I think it was forcibly foisted on all Massachusetts school children, since the house in question was only a short field trip away—I couldn’t. And it’s not that I changed my mind about the writing—actually, having reread parts now to write this column, I’m surprised that I managed to finish at all (sincere apologies to all Hawthorne fans). I didn’t.

But despite everything, The Scarlet Letter gets one thing so incredibly right that it almost—almost—makes up for everything it gets wrong: it’s not healthy to keep a secret.

I remember how struck I was when I finally understood the story behind the letter – and how shocked at the incredibly physical toll that keeping it secret took on the fair Reverend Dimmesdale. It seemed somehow almost too much. A secret couldn’t actually do that to someone, could it?

It all depends on the secret. And in this case, it actually probably could. Over several decades, Daniel Wegner, of white bear fame, has been exploring the cognitive consequences of secrecy; and what he has found is not good news for would-be secret keepers. In a series of studies in the 1990s, Wegner and colleagues found that secret thoughts not only functioned in a way that was similar to suppressed thoughts, suggesting the same cognitive mechanism underlying the two, but that they were more accessible—in other words, people more easily recalled memories that they had been asked to keep secret than memories that they had told the truth or lied about—and came to mind much more often (and more often unintentionally) than any other thoughts (so, we tend to think more often of things that we’ve kept secret, such as telling a lie, masturbating, or having a crush on someone, than we do of things we haven’t, such as losing keys or getting bitten by a dog).

Put simply, our secrets preoccupy us. The more we try to keep them at bay, the more they rise up in our minds. The more we try to fight back, the more likely we are to slip up—in another study, Wegner found that people were much more likely to give an experimenter unintentional hints about something they were supposed to keep secret than they were to say something about a word, phrase, or image that they thought the experiment knew as well; and then, they were more likely to over-compensate and give themselves away even further—and the more taxing the effort will be on our minds. In fact, Wegner does Freud (as firm an adherent of the secret-as-enemy school of thought as ever there was) one better, showing that not only do personal secrets result in outward signs of distress or trauma, but that secrecy can itself create further unwanted thoughts, further exacerbating the cycle. And personal secrets, like a stigma that can be hidden? The effects get worse quickly, getting so bad as to be termed a private hell for the secret-keeper: the more personal and personally revealing a topic, the harder the effects of keeping it hidden will strike.

Arthur Dimmesdale is certainly not alone in seeing the pernicious effects of his secret eating away at him over many years. The mechanism’s effects play out far beyond the laboratory. Numerous researchers have demonstrated that keeping family secrets, such as abuse or parentage, often results in dysfunctional households—and that keeping personal secrets related to traumatic experiences is a frequent cause of psychological and physical health problems. In fact, Holocaust victims who talked about memories that they had long kept to themselves showed a marked improvement in health 14 months after the interview—and the more they disclosed, the more they improved.

It’s remarkably taxing to keep something private. Keeping a secret means keeping up an act—and the bigger the secret and larger the audience, the greater the effort that must go into that act. And that effort isn’t just behavioral; we must also refresh it over and over in our minds. Wegner calls it the preoccupation model of secrecy: we suppress a thought; that suppression in turn causes the thought to rebound (for more on this process, you can read about his thought suppression experiments here); the rebound causes increased efforts at suppression; and the cycle continues ad infinitum.

Indeed, a secret that seemed small and inconsequential when you decided to keep it can take on a life of its own if you let it fester unattended. How many times have you not told someone something because it didn’t seem like the right time, only to find it harder and harder to say it—and to find yourself obsessing over why you didn’t, whether you should, what it all means, and on and on? Break the cycle, and you’re well on your way to freeing your mind. Only the cycle can be a tough one to break.

There’s certainly a time and a place for secrets. But before you agree to keep one for someone else—or before you decide to do something that would require you to keep one of your own—think twice. The act may be long since done, but the consequences of secrecy will remain. Just consider the fates of the two principal actors in The Scarlet Letter: at the end, it was the one who had never experienced public stigma who suffered the most. The truth often hurts, no question about it. But so does not telling it.