LONDON (Reuters - Scientists who believed they had started to decipher links between a GlaxoSmithKline H1N1 pandemic flu vaccine and the sleep disorder narcolepsy have retracted a study after saying they cannot replicate their findings.

The paper, originally published in the journal Science Translational Medicine in December 2013, suggested narcolepsy can sometimes be triggered by a scientific phenomenon known as "molecular mimicry," offering a possible explanation for its link to GSK's "swine flu" vaccine, Pandemrix.

The results appeared to show that the debilitating disorder, characterized by sudden sleepiness and muscle weakness, could be set off by an immune response to a portion of a protein from the H1N1 flu virus that is very similar to a region of a protein called hypocretin, which is key to narcolepsy.

But in a statement issued last week, the journal said the researchers, led by Emmanuel Mignot, a professor of psychiatry and behavioural sciences at Stanford University, had asked that the paper be retracted "because they were unable to replicate some of the results reported in the paper".

GSK, which has been funding Mignot's research into links between the vaccine and narcolepsy, said in a statement it believed "the original scientific hypothesis remains a valid one that needs to be further explored".

"We will continue to support Professor Mignot and his colleagues with their continued research in this area and hope these ongoing efforts will enable us to provide more answers," the British drugmaker said.

Previous studies in countries where GSK's Pandemrix vaccine was used in the 2009/2010 flu pandemic - including in Britain, Finland, Sweden and Ireland - found its use was linked to a significant rise in cases of narcolepsy in children.

Narcolepsy is thought to be brought about by loss of function in "wakefulness" cells called hypocretin cells in one of the brain's sleep centers.