Why are Americans more depressed today

US citizens are more depressed now than they have been in decades but most of them are not aware of their conditions, says a new study.

Analysing data from 6.9 million adolescents and adults from all over the country, the study found that people in the US now report more psycho-somatic symptoms of depression, such as troubled sleep and trouble in concentrating, than their counterparts in the 1980s.

"This study shows an increase in symptoms most people do not even know are connected to depression, which suggests adolescents and adults really are suffering more," said study author Jean M. Twenge from the San Diego State University in the US.

Compared to their 1980s counterparts, teenagers in the 2010s are 38 percent more likely to have trouble remembering, 74 percent more likely to have trouble sleeping, and twice as likely to have seen a professional for mental health issues.

College students surveyed were 50 percent more likely to say they feel overwhelmed, and adults were more likely to say their sleep was restless, they had poor appetite and everything was an effort - all classic psycho-somatic symptoms of depression.

"Despite all of these symptoms, people are not any more likely to say they are depressed when asked directly, again suggesting that the rise is not based on people being more willing to admit depression," Twenge pointed out.

The study appeared in the journal Social Indicators Research.