As night descends on Styal women's prison in Cheshire a deeply traumatic scene unfolds as officers dash from cell to cell, saving inmates from suicide attempts. In the first of two articles for the Magazine, Rachel Coughlan, who spent six weeks filming in the jail, describes the recurring scene.

Night is the most dangerous time in Styal, when things are most likely to go wrong. Once the women are locked behind doors, they are less able to distract themselves from their problems, be they worrying about children, the mess they have made of their lives, or thinking about past abuse.

While the first night I spent there was quiet - I'd been told this was probably down to a heroin drop - the following evening was more unsettled. At about nine o' clock it all kicked off.

Cell alarms were being pressed to summon prison officers, inmates were shouting and one girl was screaming "mummy" as she kicked her door.

The warders and nurse went from cell to cell - literally running at times - cutting ligatures, taking plastic bags from heads, patching up cuts and dealing with a suspected overdose. It finished about one in the morning.

What struck me was the casualness with which all of this was dealt with. Women who were trying to kill themselves would have whatever they'd used removed from their neck, then were almost patted on the head and locked back in - usually because there was another incident to deal with.

It's not that no-one cared, more that it was obviously so normal. Several staff told how after a bad night they tried to block out their thoughts of work.

Suicide and Styal have become inescapably linked, with the prison currently under investigation after six inmates took their own lives within a 12-month period.

"When you come on duty you never know what's going to happen" says one prison nurse. "There's always a fear of what am I going to find when I open this door. Am I going to find someone actually hanging?"

During that night at Styal I witnessed 12 incidents and over six weeks of filming, there were more than 150 examples of self harm or attempted suicide. And as one of the team comments, the figures were low that month.

Amanda Downton, who has been harming herself since the age of nine
"All female prisons are having to deal with very, very disturbed women," says Steve Hall, Styal's governor. Around 80% have a serious drug or alcohol addiction, up to 60% will been victims of physical or sexual abuse and about 30% have harmed themselves before coming into prison.

"Safe custody has become our number one priority," says Mr Hall. "You'd expect me to say it's about preventing crime but it's not. It's about keeping people alive."

He compares running Styal to having to manage some sort of a hospital, albeit one in which the prison regime comes first.

And just like a hospital, nurses figure large at Styal. Mornings, they can be found pushing medication trolleys, dispensing tablets or medicine to nearly every cell while others dish out methadone to about 80% of inmates, on one round.

One of the women, Amanda, needs a fresh cut to be bandaged up. A prolific self-harmer, both her arms are a mess of self-inflicted cuts. She has been doing this to herself since the age of nine.

"That all kicked off when I was abused. It's the only way to get him out me head really," she says.

But the nurse who is treating her cannot stick around. She is called away to revive another prisoner who is detoxing from alcohol and drugs and has collapsed but with no time to get a heart defibrillator machine, she has to deliver a sharp punch to her sternum to revive her.