Time alone heightens ‘threat alert’ in teenagers

Even when connecting online

Scientists have uncovered new insights into the impact of isolation on teenagers, revealing that even brief periods of being alone can heighten sensitivity to threats. This heightened “threat alert” response, which remains even when adolescents are interacting with others online, may provide valuable clues about the rising incidence of anxiety disorders among young people.

A recent study by researchers at the University of Cambridge focused on 40 adolescents aged 16-19, testing them before and after periods of isolation. The findings suggest that a few hours of being left alone, regardless of whether the teens were permitted to use smartphones and social media, increased their response to perceived dangers. This effect, according to the study, could be a contributing factor to the growing prevalence of anxiety and other mental health issues in young people.

The study aimed to explore how isolation influences threat sensitivity, which is often associated with heightened anxiety. While loneliness has long been recognised as a cause of discomfort, this research demonstrates how it directly affects how adolescents perceive and react to potential threats, even when they remain digitally connected.

Researchers set out to ‘induce’ feelings of loneliness in a controlled environment, conducting a series of tests, including a Pavlovian task and measuring electrodermal activity (sweat response), to monitor participants’ stress levels. They found that adolescents exposed to isolation – both with and without phones – significantly increased their threat responses. This heightened state of vigilance could explain the anxious behaviours linked to various anxiety disorders.

“We detected signs of heightened threat vigilance after just a few hours of isolation, even when the adolescents had been connected through smartphones and social media,” said Emily Towner, the study’s lead author from Cambridge’s Department of Psychology. “This alertness to perceived threats might be the same mechanism that leads to the excessive worry and inability to feel safe, which characterises anxiety.”

Evolutionary sense

The researchers noted that it makes evolutionary sense for humans to become more vigilant to potential threats when isolated, as being alone historically heightened the risk of danger. Adolescence, marked by developing independence and increased social sensitivity, is a time when these mechanisms are especially active.

The experiment, which included participants who had no prior history of mental health problems, began by establishing a baseline through various psychological tests. One was a Pavlovian threat test, in which participants were shown a series of shapes paired with a loud, unpleasant noise. Over time, the shape became associated with the fear response, allowing the researchers to measure how intensely participants reacted to perceived threats.

After the baseline tests, participants were isolated for approximately four hours in a room at Cambridge University’s Psychology Department. During one session, the teens were allowed to use their smartphones, access social media, read books, or listen to music, while the other involved total isolation with no external connections. The only rule was that participants had to stay awake during both sessions.

The heightened threat response remained despite the availability of social media and texting during the second isolation session. “Although virtual social interactions helped our participants feel less lonely compared to total isolation, their heightened threat response remained,” said Towner. This finding suggests that digital interactions may not be sufficient to mitigate the adverse effects of isolation on teenagers.

Threat responses

The results were striking: threat responses were, on average, 70% higher following the isolation sessions, regardless of whether participants used their phones. Self-reported feelings of loneliness were also significantly higher after both sessions compared to baseline levels, although the isolation with social media was associated with slightly lower feelings of loneliness.

Dr Livia Tomova, a co-senior author and lecturer in psychology at Cardiff University, who conducted research while at Cambridge, emphasised that the rapid rise in loneliness among adolescents globally in recent years is concerning. “The need for social interaction is especially intense during adolescence, but it is unclear whether online socialising can fulfil this need,” she said. “This study has shown that digital interactions might not mitigate some of the deep-rooted effects that isolation appears to have on teenagers.”

The study’s findings support the notion that isolation can directly contribute to increased fear responses, which may play a role in the development of anxiety. With loneliness among teenagers increasing, particularly in the wake of the Covid-19 pandemic, these findings may help explain why anxiety disorders are becoming more prevalent in young people around the world.

This research, published in the journal Royal Society Open Science, adds a critical new layer to our understanding of adolescent mental health. It suggests that even short periods of isolation – often overlooked in discussions about loneliness – can have lasting effects on young people’s emotional and psychological well-being.

The study reveals that the absence of physical interaction exacerbates the issue, as do the emotional and physiological changes that occur during solitary experiences.

Hero image: The University of Cambridge findings may help explain why anxiety disorders are becoming more prevalent in young people around the world. Credit: Mary Taylor