Suppressing negative thoughts might be good for your mental health after all, anew study suggests.
The findings contradict the commonly-held belief that ignoring these thoughts means they stay in our unconscious mind, influencing our behaviour and wellbeing.
University of Cambridge researchers at the Medical Research Council (MRC) Cognition and Brain Sciences Unit trained 120 volunteers worldwide to suppress thoughts about negative events that worried them.
They found that not only did these become less vivid, but that the mental health of those in the study also improved.
Professor Michael Anderson said: "We're all familiar with the Freudian idea that if we suppress our feelings or thoughts, then these thoughts remain in our unconscious, influencing our behaviour and wellbeing perniciously.
"The whole point of psychotherapy is to dredge up these thoughts so one candeal with them and rob them of their power.
"In more recent years, we've been told that suppressing thoughts is intrinsically ineffective and that it actually causes people to think the thought more - it's the classic idea of 'don't think about a pink elephant'."
When Covid-19 appeared in 2020, like many researchers, Prof Anderson wanted to see how his own research could be used to help people through the pandemic.
Dr Zulkayda Mamat - at the time a PhD student in Prof Anderson's lab and at Trinity College, Cambridge - said: "Because of the pandemic, we were seeing a need in the community to help people cope with surging anxiety.
"There was already a mental health crisis, a hidden epidemic of mental health problems, and this was getting worse.
"So with that backdrop, we decided to see if we could help people cope better."
In the study, each person was asked to think of a number of scenarios that might occur in their lives over the next two years - 20 negative fears and worries they were afraid might happen, and 20 positive hopes and dreams.
For each scenario, they were to provide a cue word and a key detail.
Each event was rated on a number of points, vividness, likelihood of occurrence, distance in the future, level of anxiety or joy about the event, frequency of thought, degree of current concern, long-term impact, and emotional intensity.
The volunteers also completed questionnaires to assess their mental health.
Then, over Zoom, Dr Mamat took each participant through the 20-minute training, which included 12 no-imagine and 12 imagine trials, where they were asked to either vividly think, or stop thinking about an event, after being given a cue word.
At the end of the third day and three months later, the volunteers were once again asked to rate each event on vividness, level of anxiety, and emotional intensity.
According to the study, at both points the volunteers reported that suppressed events were less vivid and less fearful.
They also found themselves thinking about these events less.
Dr Mamat said: "It was very clear that those events that participants practised suppressing were less vivid, less emotionally anxiety-inducing, than the other events and that overall, participants improved in terms of their mental health.
"But we saw the biggest effect among those participants who were given practice at suppressing fearful, rather than neutral, thoughts."
According to the findings, suppressing thoughts even improved mental health among those with likely post-traumatic stress disorder.
Among those with post-traumatic stress who suppressed negative thoughts, their negative mental health scores fell on average by 16 per cent, whereas positive mentalhealth scores increased by almost 10 per cent.
In general, people with worse mental health symptoms at the start of the study improved more after suppression training, but only if they suppressed their fears.
The researchers also report that one participant was so impressed by the technique that she taught her daughter and her own mother how to do it.
Funded by the Medical Research Council of the United Kingdom, and the Mind Science Foundation, the findings are published in the Science Advances journal.
Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To Know