According to a poll conducted by the University of Michigan, nearly half of teens are not ‘enjoying life’ and are dealing with issues of depression and hopelessness, the NY Post reports.

The survey results were unveiled in Dr. Jean Twenge’s book “Generations: The Real Differences Between Gen Z, Millennials, Gen X, Boomers and Silents — and What They Mean for America’s Future.

Twenge reports that nearly twice as many teens agree with statements “My life is not useful”, “I do not enjoy life,” and “I can’t do anything right” than they did a decade ago.

“These are staggering numbers, just enormous increases,” Twenge said in an interview with the New York Post. “And parents are rightfully very concerned about their children’s mental health.”

The university has been polling 8th, 10th and 12th graders annually on mental health issues since 1991.

According to Twinge, for over two decades the number of teens who agreed with those negative statement were consistently around the 20% mark. However, that changed in 2012, when they started noticing a dramatic increase in the number of teens struggling with issues of depression and hopelessness.

Twenge places much of the blame for this downward trend on the advent of social media.

READ: Number of teens who ‘don’t enjoy life’ has doubled with social media