Por que nossos cérebros são viciados em más notícias

What is negativity bias?

Negativity bias is the tendency for alarming or intense headlines to grab our attention faster than positive ones. Our brains are evolutionarily programmed to prioritise potential threats over rewards, which helped our ancestors survive in dangerous environments.

Karla Pretorius, psychotherapist and Clinical Health Lead, Orli, London, UK explains that humans have evolved to prioritise negative or threatening information over compliments and positive signals.

“Thousands of years ago, survival depended on noticing the rustle in the grass," she says. "We weren’t admiring the view - we were scanning for potential dangers. Avoiding harm was far more critical than seeking helpful stimuli.”

Even today, with no real predators around, this system still fires.

“Words such as ‘crisis’ or ‘breaking news’ can trigger it," Pretorius adds. "Especially after collective traumas such as the COVID-19 pandemic."

Research shows our emotional brain is primed to spot threats. Even unconsciously, negative stimuli trigger a dopamine hit, keeping us hooked.

Pretorius explains that this is why fear-based headlines trap us in an endless scroll - our brains are literally chasing the ‘reward’ of danger.

“Doomscrolling isn’t just curiosity,” Pretorius says. “It’s your nervous system saying, ‘If I understand everything that’s happening, maybe I’ll feel a little safer.’”

The unpredictability of online news adds to this effect. Unlike a TV show with a predictable rhythm, each new post or headline offers a variable reward - a chance of relevance or meaning - which activates your brain’s reward circuitry.

“It’s like a slot machine,” she explains.

Repeated exposure to negative news - through headlines, notifications, or social media - can keep our stress system on high alert. Over time, this low-grade fight-or-flight state leaves us tense, reactive, and fatigued.

“For example, studies show women who read negative news had stronger cortisol responses when later exposed to a stressor,” says Pretorius. “The news itself may not trigger a full fight-or-flight response, but it primes the system, making it more reactive afterwards.”

This heightened reactivity may explain why we sometimes lose our temper at home.

“We’ve been exposed to stress all day,” she notes. “So it makes sense our bodies would react to smaller triggers."

Some people view 'doomscrolling' - the compulsive habit of consuming negative news - as a modern epidemic. It’s exhausting, yet many of us find it impossible to stop.

“Doomscrolling ramps up our anxiety, but we do it anyway,” Pretorius says. “Strangely, our brain thinks it’s helping. When life feels uncertain, it searches for control in an attempt to regulate.”

Recent studies also show that doomscrolling is tied to both compulsion and coping.

“It can become a form of self-soothing - but gone sideways,” explains Pretorius. “For many people, scrolling can create a flow state. Time blurs, focus narrows, and you enter a low-demand zone. In that sense, it can serve as a temporary relief, like a pressure-release valve.”

She adds that the goal isn’t to shame this need for escape or quiet moments - it’s to bring awareness and boundaries. Without structure, even a calm moment can quietly tip into overstimulation and exhaustion. We go from ‘this is nice’ to ‘this is too much.’

Constant exposure to news can heighten stress, ansiedade, depressão, e insônia. Heavy consumption leaves stories unresolved, keeping our minds on edge.

“Our brains keep incidents open, waiting for resolution,” Pretorius explains. “Studies consistently link heavy news consumption with higher anxiety, depressive symptoms, and sleep issues. Some people watching hours of coverage during crises showed higher acute stress responses than those directly exposed to the events themselves.”

Because there’s no clear ‘off’ switch, our stress hormones - such as cortisol and adrenaline - remain elevated, delaying the natural wind-down our bodies need before sleep.

“You may feel tired but restless after scrolling before bed,” says Pretorius. “Your brain has been on high alert, like your nervous system is permanently ready for combat.”