If you’ve ever kept a secret from a friend, a family member, or a romantic partner (and you have), then the chances are good that these same people have kept secrets from you. Not all of them, and not at every moment, but some of them some of the time.

I can tell you with a fair degree of certainty that your loved ones’ secrets are about ambitions, beliefs, habits, deceptions, desires, discontents and violations of trust. In my research, I’ve asked more than 50,000 people about their secrets, and these are the themes that we often see. What I can also tell you is that as isolating as it can feel to have secrets, we are hardly alone in the ones that we keep.

In fact, data from around the globe shows that we tend to keep the same ones – around 38 different types in all. In my research, I ask people about these common categories. If each one had its own line, you could print every common secret in the world on a single sheet of paper. And when I hand this sheet over, as I often do, 97% of people say that they have at least one from the list, and they have an average of 13. This list covers the ones I already mentioned, but also includes drug use, addiction, sex, mental health, trauma, family, finances, and cheating – whether at work, at school, or on a romantic partner (current or former).

Funnily enough, we rarely get asked about our secrets. Yet even when secrets are easy to hide, this doesn’t make them necessarily easy to live with. A common reason people say that they hold back in conversation is simply because a thought about their secret came to mind.

The normal course of actions is to share with others what we’re really thinking, but to keep a secret is to veer away from this everyday act of social connection. When this happens you prevent yourself from fully engaging, blocking yourself from a chance to bond with others and get help from them.

So, what happens when we form the intention to keep a secret? As you might imagine, this increases the likelihood of hiding the secret in conversation, but it also increases the likelihood of thinking about it outside of that. In one study, we asked our participants to download an app on their phone that would allow us to randomly ping them throughout the day. Participants identified their most important secret, and indicated if it had come to mind, or if they had to conceal it in conversation since the last survey buzz. We found that the participants reported thinking about their secret, on average, one to two times every two hours. The more participants simply thought about their secrets outside of conversations, the more those secrets were harmful to their wellbeing.

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The hard part of having a secret is not that you have to hide it, but that you have to live with it, alone in your thoughts. When the only venue to work through it is your own mind, you are not likely to find the most productive way of thinking about it. Like a carousel that just never stops, each time you think back on it, you may go through the same motions, having the same negative thoughts, reiterating the same regrets, and finding yourself getting nowhere. It often takes a conversation with another person to escape the loop.

So even if you do have fears and worries, know that the research shows people react more positively to disclosures than we often imagine. You need not fear the worst, as it is highly unlikely. It might take a dash of courage to reveal something sensitive but when you take the risk, your confidant will recognise this and appreciate it. If you are in the middle of a social interaction that makes you feel comfortable and open, then recognise the door is open to disclosure, too.

You could shout your secret in a forest where there is nobody around to hear it, but just like the tree that nobody hears falling, a disclosure with no recipient is barely a disclosure at all. When people reveal secrets to others, they are often looking for help, and often seek out the people who prove most helpful. Speaking about a negative experience can have the side-effect of bringing back the negative emotions you associate it with, and this is why shouting your secret into the ether is often not enough.

Another person can offer you two different kinds of help: emotional support and practical support. If you can find someone you feel comfortable opening up to, they are likely to give you one if not both kinds. They might express sympathy or empathy, or share with you a similar struggle they have overcome. Other people can offer unique perspectives, guidance, and advice. The vicious cycle of negative thinking is easier to break when we bring others in. We can get so used to thinking about something in the worst possible way that we forget there are other ways to think about it. If you feel stuck on a secret and caught in ruminative thinking, this is a signal that it is time to change course and talk to someone.

If you are currently keeping a secret from a friend, a family member, or a romantic partner (and the chances are good that you are), then you probably have at least one more secret than you need. Chances are there is at least one too many secrets kept from you, and this is all the more reason to share what’s on your mind. When you open up to others, others will open up to you.

The Secret Life of Secrets: How Our Inner Worlds Shape Well-Being, Relationships, and Who We Are by Michael Slepian is available now (Robinson, £14.99). Buy it from guardianbookshop.com for £13.04