Scientists have found that adolescents exhibit a stronger response to perceived threats after spending just a few hours alone, and this heightened sensitivity persists even when they interact online with friends. This research provides insight into the connection between feelings of loneliness and mental health issues, such as rising anxiety disorders in young people.
Young individuals in their late teens demonstrate greater sensitivity to threats after being alone for only a few hours—this effect remains even during online interactions with their friends and family.
These results come from a new cognitive neuroscience study conducted at the University of Cambridge, which involved 40 participants aged 16-19 who were tested before and after periods of isolation, both with and without their smartphones.
As many countries face a loneliness epidemic*, the researchers aimed to simulate feelings of loneliness in teenagers and observe the consequences through various tests, including a Pavlovian conditioning task and measuring sweat response via electrodes.
The study revealed that isolation—even when participants had access to their phones—triggered an elevated threat response, which refers to heightened awareness and reactions to possible dangers. This increased alertness can lead to feelings of anxiety and discomfort.
The researchers believe that both isolation and loneliness may contribute to excessive vigilance to threats, potentially harming adolescents’ mental health over time.
They suggest that this heightened awareness of threats may explain the intense fear responses typically seen in anxiety disorders, which are increasingly common among youth around the globe.
While existing research has indicated that isolation leads to anxious behaviors and threat responses in animals, this study is said to be the first to observe these effects in humans.
The findings are published today in the journal Royal Society Open Science.
“We observed signs of increased threat vigilance after just a few hours of isolation, even when adolescents were engaged through smartphones and social media,” remarked Emily Towner, the study’s lead author from Cambridge’s Department of Psychology.
“This heightened awareness of potential threats may be linked to excessive worrying and a pervasive sense of insecurity associated with anxiety,” noted Towner, who is a Gates Cambridge Scholar.
“From an evolutionary standpoint, it makes sense that solitude would enhance our alertness to threats. This threat response mechanism undergoes significant changes during adolescence, a critical period characterized by growing independence and social awareness.”
“Our experiment indicates that isolation in adolescents could heighten their susceptibility to developing anxiety, even when they are virtually connected,” Towner explained.
The researchers recruited local youths from Cambridge, UK, carefully screening to form a group of 18 boys and 22 girls who had solid social connections and no prior mental health problems.
Participants completed initial tests and questionnaires to establish baseline measurements. These included a Pavlovian threat test, where they viewed various shapes on a screen, one of which was linked to a loud noise, creating a sense of apprehension toward that specific shape.
Electrodes attached to their fingers monitored “electrodermal activity”—a physiological indicator of stress—throughout the threat test.**
Each participant was isolated in a room in Cambridge University’s Psychology Department for two separate four-hour sessions, after which tests were redone. The average time between the isolation sessions was about one month.
All participants experienced two isolation conditions: one involved solving puzzles without any outside contact, while the other allowed them to use smartphones and access Wi-Fi, as well as listen to music and read books. The only rule for both sessions was a requirement to stay awake.***
“We aimed to replicate behaviors seen in animals isolated previously,” Towner explained. “Since animals cannot communicate feelings of loneliness, we needed to explore this aspect in humans.”
Self-reported feelings of loneliness increased after both isolation sessions, though the figures were lower after the session that included social media usage compared to complete isolation.****
However, participants reported that the threatening stimulus— the shape linked to the startling noise—was more anxiety-inducing and distressing post both isolation experiences, with electrodes indicating increased stress levels.
Overall, threat responses were recorded at 70% higher after the isolation sessions compared to baseline, regardless of whether participants engaged with others digitally.
“While virtual social engagements made participants report feeling less lonely than total isolation, their heightened threat response persisted,” Towner stated.
Previous studies have linked chronic loneliness to increased sensitivity to threats. The latest findings affirm that social isolation may directly influence heightened fear responses, according to the researchers.
Dr. Livia Tomova, co-senior author and Psychology lecturer at Cardiff University, who conducted this research while at Cambridge, remarked: “Loneliness among adolescents has almost doubled in recent years. The desire for social interaction is particularly strong during adolescence, yet it remains unclear whether online interactions can adequately fulfill this need.
“Our study indicates that digital interactions may not alleviate some of the profound impacts that isolation has on teenagers.”
Notes:
*For instance, in 2023, the U.S. Surgeon General announced an epidemic of loneliness and isolation.
**Electrodes placed on fingers detect subtle changes in sweat and corresponding variations in skin conductivity (electrodermal activity). This activity measures stress levels, which rise with emotional or physical activation.
***The baseline measures were always conducted first. The sequence of the isolation sessions was randomly assigned. Most participants used social media during allowed digital interactions (35 out of 40), with texting being the most prevalent method (37 out of 40). Other widely used platforms included Snapchat, Instagram, and WhatsApp. Participants primarily connected virtually with friends (38), followed by family (19), romantic partners (13), and acquaintances (4).
**** The average self-reported loneliness more than doubled post isolation when using social media compared to the baseline and nearly tripled after complete isolation compared to baseline.
