Martin is 20 but he claims he already knows what will kill him. The science student is one of those touched by the fastest growing epidemic in the UK - depression. And it is depression, he says, that will claim his life.

Mental illness has reached unprecedented levels in the UK according to research obtained by The Observer.

A survey of Britain's students shows that 46% of men and 64% of women show symptoms of the illness and that mental health problems are overwhelming student health services.

This compares to levels reported in 1987 where between 1 and 25% of students showed significant emotional disturbance.

"It seems that poor mental health is becoming more prevalent and more severe," said Pauline Fox, of Thames Valley University, who conducted the research for the Mental Health Foundation. She said the findings were cause for the deepest concern.

"Undoubtedly students are in poor mental shape and counselling services are unable to cope with the volume," she added.

For Martin counselling was never an option. He went to his GP and was given anti-depressants. These are currently prescribed 20 million times a year - a 700% increase in 10 years.

Government figures show that on any day around 33% of patients who visit their GP report symptoms of depression whether they recognise them or not.

"I had money and girlfriend troubles and exam worries and I wasn't sleeping," said Martin. "It took a while for me to accept that what I had was actually a mental illness. It took me even longer to recognise it wasn't an embarrassment. I'm told now that I should come off the pills and try therapy," he said.

"But although I will, and I feel a lot better than before I took the medication, I understand why people say depression kills. I know it will be the death of me sooner or later and I've got to get along with that somehow."

Depression and related suicide, suicidal behaviours and substance misuse have all increased among people in the general population.

According to Department of Health figures, around 20% of women and 14% of men in England suffer from depression at any one time but the Mental Health Foundation had estimated the true figure to be higher with symptoms affecting one in four UK adults.

Now the foundation's latest research will concern experts by showing what Ms Fox called "an alarming overview" of an illness which is still so severely stigmatised that, as studies show, employers would rather give a job to an ex-convict than to someone who admits to having ever suffered from depression.

"It is arguable whether these figures reflect the population at large or whether the tide is rising higher and faster among students,' said Ms Fox.

"The student population is far greater and made up of a far wider spectrum of people than ever before and the pressures are higher with people having to work very hard outside university to make money. There is evidence that their general health is poorer than non-students."

The epidemic of depression is spreading so fast that it has been estimated it will overtake heart disease, Aids, malaria and malnutrition to become the second most common killer in the world after cancer within 20 years.

"These are alarming statistics," said Professor Jeffrey Gray, of the Institute of Psychiatry. "What one must remember is that depression not only kills through suicide but also leads to an early death in other ways.

"It changes the structure of the brain and there is evidence now that links it to cancer, infectious diseases, premature ageing and undoubtedly dementia.

"We are designed to cope with acute stres, the kind that would see someone running from a lion. But modern stress is prolonged and evolution has not designed us to cope with that."

According to the World Health Organisation, depression is number five in the top 10 list of disabling illness and it is expected that the WHO's latest worldwide figures, to be released in June, will show a further increase.

Recent studies in the US suggest that upwards of 40% of the US population will suffer from mental illness in their lifetime.

Dr Gro Harlem Brundtland, Director-General of WHO, is making mental health a priority for 2001 with political action being urged to contain the epidemic.

"What is needed in the mental health arena is less exclusion and more care," she said. "This will be demonstrated by dismantling common myths about mental disorders and addressing the problem of discrimination."

An unpublished report by the Association of University and College Counselling, seen by The Observer, further exposes the crisis of mental illness among students.

It reveals that 12% of students at established universities contact the counselling service at some point during their student life, a rise of 25% since 1996.

Around 4.7% of students in higher education receive counselling but the services are being cut due to funding problems just as the demand is rising.