A mother woke up from a diabetic coma to find her baby had fallen off the sofa and stopped breathing.
Rebecca Raifique-King came round lying on the floor, with a rip in her top and covered in soil where a plant had fallen on her.
Paramedics were unable to resuscitate ten-month-old Jack, who had a history of breathing problems.
It was the second tragedy for the family, who lost their first-born son, Oscar, within hours of his birth.
At Worthing Coroner's Court, West Sussex coroner Roger Stone recorded an open verdict after two pathologists failed to find the cause of Jack's death.
In a statement read out to the coroner, Mrs Raifique-King, who was too distressed to attend the hearing, told of the moment she thought her second son had died in August last year.
She said she and husband Omar had been out for dinner at Mr Raifique's restaurant, Los Amigos in Montague Street, Worthing, the night before the baby's death.
Jack stopped breathing twice in the early hours of August 2 but Mrs Raifique-King comforted him and got him back to sleep both times, the hearing was told.
Mr Raifique left the house for work at 8.45am after giving his wife a shot of insulin.
But the 27-year-old housewife believes an earlier shot of the drug had become trapped in her system, causing a toxic reaction when both doses kicked in, the inquest heard.
After her husband left for work, Mrs Raifique-King said: "I took my daughter Monique and Jack downstairs and put them on the sofa to watch TV. The last thing I remember was reaching up to open the curtain."
When Mrs Raifique-King came round, her baby son had fallen off the sofa. She was woken by painter and decorator Colin Dalton, who was carrying out work on the home.
She said: "Colin was saying 'Becky, the baby doesn't look good'. I turned Jack over, expecting him to smile, but he didn't. He had brown bubbles coming out of his mouth. He felt cold and his lips were blue."
Paramedics arrived within minutes but they were unable to bring Jack round.
Professor Anthony Risden, a pathologist at Great Ormond Street Hospital, said: "In about half of all the cases of sudden death that happen in the first year of a baby's life we are unable to ascertain a cause of death."
Mr Raifique told the coroner he was bringing a claim for negligence against Worthing Hospital after his first-born son, Oscar, died in January 1999.
Oscar Raifique-King, the couple's second child, was born premature and placed on a ventilator but died within a few hours.
Mr Raifique said after the inquest the experience had been terribly distressing for his wife and himself.
A spokeswoman for Worthing Hospital said: "We have no record of any formal complaint made on behalf of this family but we are very sorry if Mrs Raifique-King feels unhappy in any way with the care she received at Worthing Hospital."
Mr Raifique, 30, also complained about the behaviour of police investigating the death of Jack.
He claimed police sent to the family home at The Drive, Goring, stood outside the door laughing after the baby was taken to hospital.
Inspector Nigel Brown of Worthing police apologised for any unsympathetic actions of his officers.
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