The average person has nine deep dark secrets, a new study has revealed. 

Researchers from the University of Melbourne asked 240 people about the things they keep hidden from others.

The results revealed that the most common secrets are about lies, followed by being secretly unhappy about appearance.

Others are about finances, while many of us keep secrets about romantic desires. 

What’s more, more than half (57 per cent) of participants had a secret sexual behaviour.

Other secrets that participants reported included physically or emotionally hurting someone, using illegal drugs, stealing something, disliking a friend, not enjoying their job or planning to propose.

‘You might think about secrets when you’re showering, when you’re doing your dishes or when you’re heading to work,’ author Dr Val Bianchi told New Scientist. 

‘Having these thoughts pop into your mind when you don’t necessarily want them to is often unpleasant, and people seem to get caught in vicious cycles of thinking spontaneously about their secrets as they go about their life, and feeling worse about them.’

The study found that people generally reported their most important secret to be negative, regularly sparking worries or concerns.

When these secrets popped into their head without warning, people reported feeling negative emotions both in the moment and also two hours later.

‘Most of the sample reported mind–wandering to what other people might think about the secret at least once during the study,’ the team wrote.

‘These frequencies suggest that people focus more on general concerns about the secret and the social impact of their secret rather than on ways to regulate who does (not) know the secret.’

However, when people thought about secrets deliberately, it was usually to daydream or fantasise about them.

The scientists also came up with ways that people could manage the wellbeing cost of keeping a secret.

When the mind wanders spontaneously to secrets, people could focus on redirecting attention, they explained.

Meanwhile thinking deliberately about secrets could be approached through purposeful reflection and constructive processing, they added.

The study, which has not yet been peer reviewed, is due to be published in the Journal of Personality and Social Psychology: Attitudes and Social Cognition.

‘Everyone has secrets at some point in time, and the most common and consequential experience people have with secrecy is mind–wandering to their secrets,’ the researchers wrote.

‘The current work is the first to systematically examine this major experience people have with secrets, capturing a fine–grained picture of how people think about their secrets, which content people think about, and to what emotional effect.’

It’s likely humans evolved to keep secrets because concealing information can protect ourselves and others from hurt., Dr Bianchi said.

‘For example, if you find out a colleague is being investigated at work, you might choose to stay silent about it, rather than gossiping with others, to safeguard their reputation within the organisation.’

In some circumstances, however, confessing secrets can provide some relief – especially when telling people who aren’t directly affected by the information.

This is why particular professionals, such as therapists, can help people deal with the burden of secrets.

The research has been funded by the Australian Office of National Intelligence, whose operatives may need strategies to help bear the responsibility of secret–keeping.

A previous study, published in 2023, found that keeping secrets could actually be good for you.

Lead author Michael Slepian, from Columbia University, said: ‘Decades of research on secrecy suggest it is bad for our well–being, but this work has only examined keeping secrets that have negative implications for our lives.

‘Is secrecy inherently bad for our well–being or do the negative effects of secrecy tend to stem from keeping negative secrets?

‘While negative secrets are far more common than positive secrets, some of life’s most joyful occasions begin as secrets, including secret marriage proposals, pregnancies, surprise gifts and exciting news.’

The study revealed that participants who reflected on their positive secrets reported feeling more energised than the participants who thought about their good news that was not secret.

Those who reported that they intended to share their news with others also said they felt more energised.