In fact, according to a study in the Journal of Personality and Social Psychology, people keep 13 of them on average. The most common secrets are sexual in nature, researchers found: either having to do with behavior or having romantic thoughts about someone outside of the confines of your primary relationship. But all secrets, big and small, have a profound effect on you and your marriage — whether you notice it or not. Secrets in relationships are common. But a body of research suggests they can negatively affect mental health and even physical health. Secrets become a problem because people’s minds tend to often wander to the secrets they’re keeping, which can lead to a reduced sense of well-being, concluded Columbia Business School professor Michael Slepian, Ph.D., lead author of the above-mentioned study. Slepian’s study is just the most recent looking at the effects of secrets. A 2012 paper suggests that keeping secrets from a partner makes him or her less trustful of the secret keeper, which creates a cycle that ultimately damages the relationship, wrote lead author Ahmet Uysal, Ph.D., a professor at Middle East Technical University. In a study Uysal published the previous year, he wrote that concealing negative personal information lowered subjects’ tolerance of pain. Belgian researchers found that “important, unhappy” secrets had negative effects on health and tended to cause more shame and guilt than revealing them did. A study out of the University of Santa Barbara suggests that unloading secrets seem to help people to stop stewing about the secret and increases the self-esteem of the revealer – but only when they got a positive response from the person who heard it. Scientists, it’s pretty obvious, are fascinated by secrets. It would be a mistake, however, to oversimplify the research findings and assume secrets always cause harm, and revealing them always makes things better. “It’s difficult to generalize about the body of research that secrets are bad for you,” says Dr. Karl Pillemer, Ph.D., a sociologist at Cornell University and the author of 30 Lessons for Loving: Advice from the Wisest Americans on Love, Relationships, and Marriage. “Many of the studies were small in scale and involved artificial situations, and I’m not sure how well those translate into actual human behavior and well-being.” RELATED: 5 Ways To Make Men Insanely Attracted To You (As Written By A Man) Take the study concluding that revealing secrets made people feel better as long as they weren’t judged harshly for what they told. It’s just as likely that the study revealed subjects’ gravitation toward people who would tell them what they wanted to hear as it reflected a cathartic effect from revealing a secret to just anyone. “If you’re cheating on your wife, for example, it might be helpful to vocalize it, but you’re probably going to choose a person to tell who will align with you, not the friend across the country who goes to church every Sunday and has had one sexual partner his entire life,” says Dr. Christine Hyde, Ph.D., a licensed clinical social worker, and certified sex therapist. There’s enough evidence to conclude, however, that, for a significant number of people, secrets can cause stress and anxiety and affect the health of relationships. “At the most basic level, we’re about survival, and by connecting with people on a primal level, we improve our chances of survival,” says clinical and forensic psychologist Dr. John Paul Garrison, PsyD. “When we keep secrets or are being deceptive because we think we’ll be rejected by people, it increases the body’s insulin and cortisol, which can create heart palpitations and affect the brain.” These effects heavily depend upon the individual, however, Garrison notes. If lying to a partner or hiding something damaging doesn’t make a person anxious, they’re not going to experience those signs of physiological stress. Psychopaths, sociopaths, and narcissists, for example, won’t be bothered in the slightest by lying to others or hiding things, he says. However, if you’re in a relationship with a narcissist and have a secret, you might want to keep it to yourself. “Revealing secrets to narcissists only gives them more ammunition to degrade you, which really goes back to the quality of a relationship,” he says. Although how well you can emotionally handle secrets does have to do with your sense of morality and empathy for other people, it’s not cut and dry. “Highly moralistic people will find it torturous to hold onto a secret, and for them, it can lead to IBS, anxiety, and chest pains, absolutely,” Hyde says. “But I also think some of this research pigeonholes people in societal standards that aren’t realistic. The reality is that people cheat all over the place and are dishonest.” Hyde says it’s “a lovely benchmark” to assume that most people will suffer negative effects when they’re not honest with their partners about serious things they might be hiding, such as cheating, a gambling or drug problem, bad investments, losing a job, or criminal behavior. Most people, however, are honest because of one thing: fear. RELATED: 46 Clear (If Unexpected) Signs A Guy Likes You “They think, ‘bad stuff will happen if I lie — I’ll be the one who gets caught, or arrested or loses everything,’ so they’re afraid,” she says. Even if you’re never caught in a lie and don’t feel anxious about the secrets you’re keeping from your partner, marriages can suffer slow and subtle negative effects due to secrets and lies. For one example, the mind-wandering aspect of secrets that Slepian wrote about in his study undeniably saps attention from your primary relationship. Or, say you had a fling with a co-worker that your wife doesn’t know about, and you’re suddenly struggling to explain your desire to avoid work events or why you want a new job when your career had been going so well. Your wife might be confused or suspicious and therefore trust you less, or if she believes your explanations, you might feel like a jerk, which also could increase the distance between you. In addition, Hyde says, if you’re cheating and your partner thinks she’s in a faithful and monogamous relationship, you’re robbing her of her free will to make informed decisions about your relationship. “The index is if there’s guilt and shame involved, that’s taking up your mental energy,” Pillemer says. Having secrets saps mental energy and does tend to wear on most people over time, Garrison agrees. “Meeting things head-on is almost always universally better,” he says. “If it’s something you can live with and you don’t value the other person knowing the truth, it’s up to you. But you might have to take a risk. If it matters to you to be completely honest, you have to find a way, to tell the truth.” Truthfulness does appear to be a major factor in keeping couples happy in the long term. In his interviews with older people for The Legacy Project at Cornell, Pillemer says that couples cited honesty and open communication as the two most important elements of a successful, lasting relationship. When asked what they regretted most, the number one answer was that they weren’t able to be fully honest with their partners. But it’s also true that the risks of revealing secrets can be real and devastating so should be considered carefully. RELATED: How Science Can Predict If You’ll Be Friends With Your Ex Porn habits are surprisingly common deal breakers in many relationships, Garrison says. A husband revealing past homosexual experiences also has proved to be too much for some wives in his practice to handle, he adds. Telling a partner about a history of sexual abuse might not be helpful if a partner isn’t equipped to handle the information and be supportive, Hyde says. Hyde also had a counseling client who was outraged and disgusted that her husband expressed his desire to have sex with her from behind, a position a lot of couples would consider pretty vanilla. “It’s really sad when someone opens up and their partner rejects them,” Garrison says. “Hopefully, your partner sees value in sharing secrets that deal with authenticity, difficult experiences, and/or learning from mistakes. If revealing a secret to your partner causes them to reject you then it may not be a good-quality relationship in the first place.” Many people decide to reveal a secret such as cheating to move forward in a relationship, despite the risks, Garrison says. This article was originally published at Fatherly. Reprinted with permission from the author. Hyde approaches clients with damaging secrets in a similar way, advising that they figure out their cognitive distortions, which she defines as the stuff you tell yourself to allow yourself to engage in what you know is bad behavior. “Cognitive distortions minimize, legitimize, or justify our bad behavior,” she says. “At a minimum, you need to take an inventory about that.” Pillemer says that honesty isn’t something that comes naturally to everyone. It’s something his study subjects, who were 65 and older and grew up in a time when people weren’t as honest about sexual behavior and desires, for example, often had to learn how to do. But when they reflected on what makes for strong relationships, honesty topped the list. “When we asked them if they wanted their partners to be honest about what might’ve gone on when their partners were away in the military,” for example, he says, “Most said they wanted to know. It helped cement relationships.” RELATED: 15 Men Reveal The Painful Reasons They Regret Marrying Their Wives Virginia Pelley is a former women’s magazine editor, investigative reporter, and essayist who has written health and fitness content for Men’s Journal, Cosmopolitan, Chicago Tribune, and the Washington Post, among others.