Most of us have that one Facebook friend who keeps posting the most depressing news stories time after time, or maybe you yourself can't look away from rolling coverage of mass shootings or natural disasters, but it seems there's a psychological reason that we find these awful events so compelling.

A new study shows that repeated exposure to "collective trauma" – like the Boston Marathon bombing in 2013, or the devastating aftermath of Hurricane Maria in 2017 – leads to a cycle of distress and even more 'bad news' consumption.

Based on three years of research following a sample of 4,165 people in the US, those that end up watching more news coverage of these events are more likely to feel worried about the future, and more likely to spend more time watching the news when the next upsetting story hits the headlines.

cycle distress more(UCI)

That in turn repeats the cycle, leading to even more distress and media use, according to the team behind the new study.

"It's natural for people to experience feelings of concern and uncertainty when a terrorist attack or a devastating hurricane occurs," says one of the researchers, psychologist Roxane Cohen Silver, from the University of California, Irvine (UCI).

"Media coverage of these events, fuelled by the 24-hour news cycle and proliferation of mobile technologies, is often repetitious and can contain graphic images, video and sensationalised stories, extending the impact to populations beyond those directly involved."

The research was bookended by the 2013 Boston Marathon bombing and the 2016 shooting at the Pulse nightclub in Orlando, Florida. While previous studies have spotted a link between watching a lot of news coverage of these events and negative effects on mental health, this time the focus was on the longer term effects over time.

In this case the volunteers were interviewed four times between 2013 and 2016 – between two and four weeks after the Boston bombing, six months after the bombing, two years after the bombing, and five days after the Pulse massacre.

The researchers found a link between higher news consumption after the Boston bombing and posttraumatic stress six months later; those same people were then more likely to tune into extended coverage of the Pulse shootings.

"Our study is unique in that it is the first to demonstrate the pattern of repeated media exposure to mass violence and distress over time and over the course of multiple events, among a large sample of individuals who were followed for several years," one of the team, psychologist Rebecca Thompson from UCI, told Ed Cara at Gizmodo.

"For media outlets, we recommend a moderation of the sensationalistic aspects of the news coverage of these events, so as not to incite excessive worry and distress among viewers."

The researchers admit that watching rolling news coverage and staying glued to social media when something terrible happens is understandable – we want to find out what's happening in the aftermath of these events and how we can stay safe.

At the same time there's a balance to be struck. Spend too much time watching and reading and hearing about these tragedies, and it can start to send us into a miserable spiral that's then hard to get out of.

The added stress brought on by concentrating too much on coverage of these events could raise the risk for other stress-related problems further down the line – and so media organisations and social media companies should take a more considered approach, the researchers suggest.

"The cycle of media exposure and distress appears to have downstream implications for public health as well," says Thompson.

"Repeated exposure to news coverage of collective traumas has been linked to poor mental health consequences – such as flashbacks – in the immediate aftermath and posttraumatic stress responses and physical health problems over time, even among individuals who did not directly experience the event."

The research has been published in Science Advances.