4.48 psychosis, King's Theatre, Edinburgh Festival

Darkness and light

First performed posthumously at the Royal Court in 2000, Sarah Kane's 4.48 Psychosis – a highlight of the International Festival's programme – gets right to the heart of the subject of suicidal depression. It takes the audience inside the mind of someone in the grip of a severe illness, spinning through feelings of uselessness towards thoughts only of oblivion.

Kane, whose brilliance as a writer was cut tragically short when, aged 28, she took her own life in 1999, gained a reputation as a genius tortured by reality. This has apparently made her a kind of pop icon in Germany, her work featured prominently there and in Poland, and in countries from Turkey and Korea to Japan and Mexico.

Unlike some productions, which have played down the undeniably autobiographical element in the play, TR Warszawa's compelling production, spoken in Polish with English subtitles, chronicles Kane's mental unravelling, her bleak prose-poem (her final work) reflecting a painful disintegration. 4.48 is the time of night at which Kane often woke, according to her friend and fellow-playwright David Greig.

Yet despite the dark subject matter and the grim inspiration behind it, Kane's script buzzes with a sizzling energy, occasionally funny and always piercingly sharp. Yet, harrowing and illuminating, it's not an easy ride and neither should it be.

With a cast of seven, Grzegorz Jarzyna places the action in a bland white space with minimal set. Along the back wall is a row of basins and mirrors, at the front a table, a couple of steel chairs and a Perspex partition, the stage cinematically lit by Felice Ross in swirls and shafts of light that seem to dissolve. The audience's attention is riveted almost entirely on the central character, based here on that of Kane herself, played with a terrifying intensity by Magdalena Cielecka.

Acting as though anguished beyond reason, Cielecka writhes and clutches at the air and also herself as the key protagonist confronts her interior devils and a series of anonymous figures – a fellow sufferer perhaps, a couple of medics possibly, and a persistent and loyal female lover.

The soundscape ranges from a mechanical, out-of-tune musical cacophony to a booming, ironic burst of "When I Fall in Love". Numbers projected on to a screen add to the general feeling of anxiety. This repeated motif, "serial sevens" or counting down from 100 in sevens, is taken from the psychatrist's box of tricks to test a patient's concentration. No one could fail to concentrate on the sort of countdown we were witnessing here. Cielecka's searing performance left no room for any doubt as to the end result.