Teenagers' behavioural and emotional problems have increased in the last 25 years, a report says.
Teenagers are getting contradictory messages, experts say
Lying, stealing and disobedience were more common for both girls and boys, London's King's College and University of Manchester researchers found.
The study, of 15 and 16-year-olds in 1974, 1986 and 1999, also said anxiety and depression were rising.
The findings are due to be published in the Journal of Child Psychology and Psychiatry in November.
The report suggested declining mental health could not be linked to background as there were parallel increases across social groups and all types of families.
Emotional difficulties have increased significantly since the mid 1980s while behavioural problems more than doubled for boys and increased by a third for girls over the 25-year period.
However, the rise in behavioural problems was mainly confined to "non-aggressive" actions such as lying and disobedience rather than fighting.
The findings were in contrast to a similar study in the US, which found that from 1989 to 1999 anti-social behaviour had fallen.
And a recent World Health Organisation study of 162,000 of 11, 13 and 15 year-olds in 35 countries warned the UK had "worryingly high levels" of behavioural problems.
Report author Dr Stephan Collishaw, from the Institute of Psychiatry, said: "Most teenagers are well-adjusted but it has long been known that a minority do face emotional and behavioural problems.
"It is of great concern that this minority has grown substantially over the last 25 years.
"Reversing this trend will need a clearer understanding of why young people today are at greater risk than their predecessors."
Dr Ann Hagell, research development adviser at the Nuffield Foundation (NF), told BBC News Online it was impossible to fully explain the change.
"I think it has got something to do with the lengthening transition from adolescence.
"People are not leaving home until their mid 20s yet they are getting inundated with media images of things they should buy.
"We demand that teenagers become responsible without giving them the means to become so."
Dr Hagell said she hoped the research, which was commissioned by NF, would raise awareness about how adolescents were treated.
"The focus on adolescents at the moment is on youth offending, anti-social behaviour and exam results.
"That is a simple model. We need to look at the bigger picture. What are the consequences for those who don't make the grade?"
Lying, stealing and disobedience has increased since 1974
Jacqui McCluskey, a senior policy officer at children's charity NCH, agreed the transition from adolescence to adulthood was at the root of the problem.
"As a society we are sending out a contradictory message on children and they pick up on this.
"We have high expectations with exam targets but then legislation on anti-social behaviour also defines them as problematic.
"At the same time there is an attachment issue. We are not giving teenagers the emotional support they need, a hug and love."