Dock officers called for an ambulance soon after Sean Keena was convicted of the brutal murder of Mark Long.
Keena kicked Mr Long to death during a violent outburst at the homeless charity property where they were both living.
A judge said Keena may never be fit to be released from prison as he imposed a life sentence.
Mr Long, 45, suffered catastrophic brain injuries as he was kicked and stamped on by Keena during the prolonged attack.
Keena must serve a minimum of 16 years behind bars before he can apply to the parole board for release.
Mr Justice Dingemans said Keena may never be released due to his unpredictable violent outbursts.
Keena was unanimously found guilty of murder by a jury this afternoon after a seven-day trial.
The judge ordered the 39-year-old defendant to be removed from court after the verdict when he kept shouting as he was about to be sentenced.
A dock officer returned to the court a short time later to tell the judge that Keena had had a fit and an ambulance had been called for him.
Jurors heard Mr Long was found in the blood stained hallway of the house on South Bailygate in the early hours of August 23.
Keena and his victim were among four residents at the house run by The Saviour Trust, and their regular drunken arguments were so disruptive that a fellow resident had asked to be moved.
Keena had also threatened to attack Mr Long on a previous occasion, causing him to smash a window to get out of the property.
Examination of Mr Long's body showed him to have been subjected to a “prolonged and vicious” beating, during which Keena stamped on him at least twice.
It appeared Mr Long tried to crawl up the stairs to escape harm during the “death struggle”, only to be dragged back down and eventually lose consciousness..
Keena denied the murder charge. He claimed he had woken in the night and found Mr Long injured in the hallway.
A statement was read to the court on behalf of Mr Long's sister, Deborah Gill, who sat in the public gallery throughout the trial.
She said: "Mark was not only my brother, but he was my best friend and my soulmate.
She added: "Myself and my family are living a life sentence, not the man who did it, because he is still breathing."