Depression and anxiety are treatable with medication and counselling, but one of the most insidious things about mental illness is that only a third of the population has access to treatment and almost two-thirds of those with mental ill-health get no treatment.

There are more people suffering depression right now than there are with a common cold. And there are even more than that with anxiety disorder.

Mental ill-health is statistically normal. Indeed it is common, led by anxiety and depression. Half of us will experience at least one period of mental illness in our lives. As many as 4 million people in Australia experience mental ill-health at any given moment. Young people are in particular need; as many as one in four of them is currently experiencing a mental health issue.

Almost everyone who dies by suicide exhibits warning signs, which is a compelling reason why people should be informed about what to look out for and where to find professional help. This coming week is Mental Health Week, an opportunity for people to learn about how to help themselves and each other.

I have been feeling that terrible tightness in the chest, the crippling fatigue, the sleeplessness and the restlessness that are common signs of anxiety disorder. As it turns out, it is the direct, mongrel effect on my metabolism of a tumour in my pituitary gland – which is almost certainly benign but is certainly growing and so is about to come out. The prognosis is excellent, and the surgery relatively low risk – although the thought of it has probably added to the feelings of anxiety. In all probability, I'll be fine – and meanwhile have benefited from having an insightful taste of what it must be like to suffer clinical anxiety. Should you suspect you or someone else might be experiencing undue anxiety, there is a checklist on the beyondblue website.

My recent unpleasant experience has buttressed my view that one of the key reasons the proposed plebiscite on marriage equality is a monumentally stupid idea is the risk it poses to young LGBTIQ people. It's a view informed by research. For the past five years, I have been a board member of the Young and Well Co-operative Research Centre, a national collection of private-sector firms, universities, government and not-for-profit organisations that funded and conducted research into mental health and the wellbeing of young people.

One of the most important studies done by the Young and Well CRC is a report called Growing Up Queer. It proves that the unfair treatment of non-heterosexual people is a life-and-death matter. The study found 16 per cent of GLBTIQ young Australians had attempted suicide and a third had harmed themselves, largely due to homophobic harassment. It found more than four in 10 had thought about self-harm or suicide – making them six times more likely to consider taking their own life than their heterosexual peers. As many as two in three LGBTIQ young people have been bullied about their sexual orientation. The study found widespread homophobic harassment and violence in schools, at work and at sporting events.

It's not just young people in danger should the massively wasteful, hurtful and utterly unnecessary plebiscite proceed. One in five LGBTIQ people in Australian is currently experiencing depression – more than triple the rate of heterosexuals. And as many as one in three LGBTIQ people is currently experiencing an anxiety condition – twice the rate of heterosexuals.

These facts are at the heart of a national push to get our politicians to dump the plebiscite and do their bloody job by voting in Parliament on a same-sex marriage bill. One of the nation's leading advocates for early intervention and for raising awareness about mental health, former Australian of the Year Professor Patrick McGorry, is publicly warning that the plebiscite increases the risk of self-harm and suicide by LGTBTIQ people. It's a message he delivered personally in recent days to Opposition Leader Bill Shorten, who has rightly been raising such concerns for months.