It’s not uncommon for teens who drink, abuse substances, or have behavioral problems to be perceived as having a high risk of mental health problems. But although these behaviors tend to be more obvious, there’s another group of behaviors that are “invisible” to those who aren’t paying attention. According to a new study, cell phone use, sleep deprivation, and a lack of exercise, together, can point to psychiatric illness in teens.

Anyone who has a Facebook or Twitter account has likely come across someone who spills their life’s troubles into status updates — something that might be more apparent among teens. But becoming a recluse, and staying up all night to use some form of media, whether it’s a TV or the internet, can cause a teen to lose sleep, and subsequently, the will to exercise. These behaviors may indicate that a teen is at risk of anxiety, depression, and suicidal thoughts, the researchers said.

Adults who see teens partaking in these activities “do not generally perceive these behaviors as particularly harmful for reasons for concern,” the researchers from the Karolinska Institute in Sweden wrote. “Nevertheless, the high- and the invisible-risk groups have a very similar prevalence of depressive symptoms, anxiety symptoms, and suicidal thoughts.” Their results appear in the journal World Psychiatry.

The study involved over 12,000 adolescents throughout 11 different European countries. They were asked about various risk behaviors — drug/alcohol use, sleep time, missing school — that have been linked to psychiatric symptoms. Once their answers were organized, it became clear that besides the high- and low-risk groups, there was also the “invisible” risk group. “As many as nearly 30 percent of the adolescents clustered in the ‘invisible’ group that had a high level of psychopathological symptoms,” said Vladimir Carli, of the National Center for Suicide Research and Prevention of Mental Ill-Health at the Karolinska Institute, in a statement.

Finding a solution may be difficult but not impossible. According to previous studies, the three factors putting teens at risk — media use, sleep deprivation, and physical activity — may all be interrelated. Reducing media use, for example, especially during the nighttime, could help teenagers sleep more because they’re helping their body produce melatonin, a hormone responsible for helping us sleep. In turn, this could lead to a domino effect, in which teens are more energetic, performing better in school and being more physically active. The end result: more happiness. Of course, treating already-present psychiatric problems will take other efforts.

The researchers concluded that earlier intervention was key to tamping down on these issues among teens. “The results of this study confirm the need for early prevention and intervention in the mental health field,” the researchers wrote. “The most common risk behaviors among girls are a reduced number of hours of sleep and a sedentary lifestyle, while drug and alcohol use are more common among boys. Thus, preventive interventions should be tailored specifically for boys and girls.”

Source: Carli V, Wasserman D, Hoven C, et al. A newly identified group of adolescents at “invisible” risk for psychopathology and suicidal behaviour: Findings from the SEYLE study. World Psychiatry. 2014.