Two sisters of Ben Cowburn, who was found dead at a mental health unit in Cornwall, left the hearing while the coroner was summing up at his inquest.
Ben, who was 18, died at Longreach hospital in Redruth in December 2010.
He was found in his room with a plastic bag over his head. He died from asphyxia.
The coroner told the jury that a nurse had checked on Ben an hour earlier and he appeared fine.