A four-year-old boy died after inhaling his own vomit when he should have been watched by nurses.
An inquest was told that one nurse went on a two-hour break when she was due to monitor Daniel Hames, who had acute gastroenteritis.
Daniel's mum Christina was sleeping in a chair by his bed but when she woke up in the morning she saw a nurse stood over him.
She told her son's inquest in Doncaster: "I jumped up and I just saw my son lying there. He was on his back, not moving. I said to him, 'don't leave me, don't leave me'."
But Daniel had died at around 7.30am. A member of staff was sacked following the tragedy.
The inquest was told Daniel had been vomiting the day before and had already been seen at Doncaster Royal Infirmary on the day of his death.
The doctor advised his family to take him home, but hours later he had to be rushed to A&E by ambulance.
He was admitted to a paediatric ward and examined and given a drink, but the inquest heard he was not assessed at regular intervals over his six and a half hours in hospital.
The coroner's court heard a nurse was told by a colleague to carry out observations, which she did not do because she was on a two-hour break.
Asked if the length of the break was normal, the hospital's matron said: "It was not acceptable nor, am I aware, common practice."
The cause of his death in March 2013 was given as acute aspiration of stomach contents due to adenoviral gastroenteritis.
During the inquest it became clear staff could not access Daniel's full medical history.
He had been ill several times with the same condition the year before and spent four days in hospital in June 2012.
He had also been sent home from school suffering from diarrhoea in February 2013.
Assistant coroner John Sleightholme said 'communications in some way could have done better' but ruled the death was due to natural causes.