LONDON - Dr Dylan Griffiths has spent more than 20 years healing the minds of troubled teenagers. But the British psychiatrist is shocked by what he is now facing on a daily basis.

He is treating record numbers of disturbed young patients, unable to cope with the pressures of modern life, who are hooked on drink, drugs and underage sex, or who are so desperate they even contemplate suicide.

The age of experimentation among Britain's teenagers is dropping every year, he and other leading health workers warn, creating a mental health time bomb which will create a generation of dysfunctional adults.

"For today's teens, marijuana, cocaine and alcohol are as ubiquitous as traffic on the street," said Griffiths, who is based at Ticehurst House Hospital in East Sussex.

"Adolescents who self-harmed were rare 30 years ago. Today, self-harming is a dramatic, addictive behaviour, a maladaptive way for growing numbers of youngsters to relieve their psychological distress."

The shocking extent of teen angst among Britain's youth is revealed in a report into adolescent mental health.

Backed by counsellors, drug experts and mental health charities including Sane, the independent study commissioned by the Priory Group paints a bleak picture of the growing mental-health crisis among 12 to 19-year-olds.

Family break-up, increasing pressure to achieve at school, a lack of tolerance in society and an "anything goes" attitude are all contributing to a rise in the number of young people pushed to the brink of suicide, with others driven to experiment with drugs, drink and underage sex as a way of coping with stress.

More than 900,000 adolescents have been so miserable they have considered suicide, the study says. A million have wanted to self-harm and more than half a million have experienced bullying or violence at home.

The Priory research is based on interviews with 1000 girls and boys across the country as well as an analysis of figures provided by the Office of National Statistics.

More than one in seven 14-year-olds and one in 25 13-year-olds said they had had sex with a friend. Around one in every 13 teenage boys and girls said peer pressure had led them to go through with sex.

Peer pressure was also to blame for many adolescents using alcohol or drugs - one in 20 13-year-olds and around one in six 15-year-olds - had experimented with illegal substances, believing it would make them look "cool" and be better accepted at school.

Another worrying trend is the increase in teenagers who have such low self-esteem that they think they need radical surgery to make them look "normal".

Nearly one in five 15-year-old girls and boys and one in every 20 13-year-olds said they had considered plastic surgery.

Counsellors, drug experts and mental health charities agree that action is needed urgently to prevent a generation of young people growing up with serious mental health problems.

Dr Angharad Rudkin, a children's therapist, said that the internet and mobiles, which have given rise to text bullying, were factors.

"There is a lot more stress now in the education system and a pressure on teenagers to be thin, beautiful, successful and to have sex," said the clinical psychologist based in Basingstoke, Hampshire.

"There's less guidance for teenagers, less mentoring and fewer role models for positive behaviour."

Marjorie Wallace, chief executive of Sane, said that increased availability of drugs was a huge factor in the rise in young people suffering from mental illness.