A coroner has concluded it is "most likely" that a nursery nurse developed the sleep disorder narcolepsy as a result of receiving a swine flu vaccination.
Katie Clack, 23, became depressed after developing the condition in 2009 and jumped to her death from the top of a multi-storey car park in Peterborough in September 2014.
Her narcolepsy had led to her sleeping for up to 19 hours per day on occasions and her mental health worsened.
An inquest in Stamford heard that the Peterborough woman did not want the vaccine but was required to for her job.
Recording a narrative conclusion, Paul Cooper, acting senior coroner for South Lincolnshire, said studies showed there were "significantly raised odds of narcolepsy after (being given the) Pandemrix" vaccine in those aged 18 and above.
"On the available evidence on the association between vaccination with Pandemrix and onset of narcolepsy it seems most likely that receipt of this vaccine in December 2009 caused Miss Clack's narcolepsy," said Mr Cooper.
He added that narcolepsy triggers depression, though he noted the case of Ms Clack was "complex and very rare".
Ms Clack's family is represented by Peter Todd and Freya Colvin, of law firm Hodge Jones & Allen.
A statement issued on behalf of the family said: "Katie was an energetic young woman who had just discovered her passion working with children.
"Narcolepsy turned her life into a terrible daily struggle and drastically reduced her quality of life.
"We cannot believe she would have decided to take her own life had the balance of her mind not been disturbed."
Ms Colvin added: "The Clack family has waited a long time for this inquest.
"It is important that the coroner has recognised the causal link between the vaccine and narcolepsy and the devastating impact this had on Katie's short life."