Is there a connection between mental health problems and poetry? The contemporary British poet Roddy Lumsden has written that "a poet confessing to mental illness is like a weight lifter admitting to muscles," a statement that personally makes me wince, but it is undoubtedly true that a great many poets are considered to have suffered from mental illness; John Clare, Robert Lowell, Sylvia Plath and Theodore Roethke to name just a few. Is there something about the emotional extremes of bipolar disorder, for example, that is conducive to poetic expression? Or is it the other way round? Can writing poetry send you over the edge?

I recently chaired an event for the charity Poet in the City as part of the Words on Monday series, held in London at Kings Place, the Guardian's new home. Poet in the City is a charity committed to attracting new audiences to poetry and the evening was the latest in a series of events it has held on mental health related themes.

Entitled The Divided Self (from RD Laing's book of the same name, first published in 1960), the evening featured readings by four contemporary poets, Simon Barraclough, Suzanne Batty, David Constantine and Sarah Wardle, followed by a short discussion. Batty and Wardle have both 'done time' on psychiatric wards and written resonant, gutsy and humorous poems about their experience. Batty also leads workshops for people who have experienced mental distress.

The evening was billed as being on the subject of poetry and mental illness. But was it actually helpful, I asked the poets, to even think in those terms? Were we not creating an artificial boundary between 'sanity' and 'madness', when what we were actually talking about was a range of human experience, however extreme it might be? David Constantine reacted quite strongly to this. While bipolar-type mood swings were characteristic of the poet's creative cycle, severe mental illness was characterised by a lack of flexibility, a mental rigidity, quite the opposite of the 'chameleon self' that poetry required.

It may be that during periods of acute psychosis, for example, this is true. But in my own experience, one of the enduring legacies of a 'breakdown' is a vastly increased flexibility, a smudging of the boundary that used to divide 'the real' from 'the imagined'. Once you realise that the world you perceive is precisely that, the world you perceive, and not an objective reality, it's impossible to unrealise it again.

I am wary of romanticising 'madness' in any way, and I certainly believe that severe depression has robbed us of far far more than it's given: what might Sylvia Plath have written had she not killed herself aged 30? But it does seem to me that for those who survive, poetry can offer a powerful means of expression.