A 78-year-old woman ran herself a bath and drowned in a mental health hospital after her observations were reduced to an hourly check.

Joan Darnell, who had dementia and bipolar disorder, had been sectioned after she pointed a knife at her daughter.

She was taken from her home in Field Grange, Lowestoft to the Julian Hospital in Bowthorpe Road, Norwich and initially put on observations four times per hour, later upped to six times per hour.

Staff reported that she would pace up and down corridors, get into altercations and that her 'intrusive' behaviour made her vulnerable.

But her observations were later reduced to an hourly head count and she drowned the next day on October 16, 2014, an inquest heard yesterday.

Mrs Darnell, who was the widow of a retired garage proprietor, was on the Blickling ward of the Julian Hospital, with around 15 other elderly patients presenting with memory problems.

Senior coroner Jacqueline Lake told a jury they would hear evidence about how Mrs Darnell was able to enter an unlocked bathroom on the ward, run a bath and drown.

A post-mortem report found that Mrs Darnell had bruising consistent with a fall into the bath and an impact to her head which suggested this was accidental.

A written statement from Mrs Darnell's daughter Dee explained that her mother had a breakdown after the death of her husband, who was her sole carer.

While she moved from London to be closer to her family, she 'hallucinated, talked constantly, could not stay still at all' and was sectioned on September 23, 2014 after the knife incident.

Nurse Adelaide Hampton said a care plan was written the day after Mrs Darnell's arrival at the Julian Hospital, and patients were always accompanied by two members of staff to have a bath.

But charge nurse Andrew Stone said bathroom doors were not routinely kept locked as patients needed to access toilets.

Dr Ibanibo Braide said care arrangements were discussed at daily meetings, and notes showed Mrs Darnell appeared 'more settled' when her observations were reduced.

But he stressed the observations system was 'not set in stone' and could be changed throughout the day by nursing staff.

He added staff tried not to escalate observations, adding: 'We try to make patients as comfortable as possible in spite of the challenging nature of their presentation.'

The jury inquest, that is set to last three days, continues today.