The Health Service Executive says it is actively investigating a link between narcolepsy and the Pandemrix vaccine for swine flu.

The Executive confirmed today that it is aware of 29 new cases of potential narcolepsy in children and adolescents.

The vaccine for the H1N1 strain of influenza was administered here in the winter of 2009 to 2010.

The HSE says it has written to all GPs, psychiatrists and consultant paediatricians to ask them to look out for the signs of narcolepsy - a chronic and debilitating sleep disorder.

The Pandemrix vaccine is no longer on offer here and the European Medicines Agency (EMA) recommended restricting its use, while a possible link to narcolepsy is investigated.

An increase of the condition was reported in children and adolescents in Finland and Sweden following the H1N1 pandemic.

Having looked at this research the EMA says it is satisfied the vaccination led to an increased incidence of the condition in those under 20.

But the Assistant Director of Health Protection at the HSE, Kevin Kelleher said today that the swine flu vaccine was offered to people based on evidence available at the time.

He said it was a benefit versus risk decision and people were saved from spending time in hospital and from death.

He said the HSE is making contact with families who have been affected and is seeking advice from Scandinavian countries over what can be done to help.

A new support group SOUND - for Sufferers of Unique Narcolepsy Disorder - will be launched in Dublin tomorrow.