A mum claims her son sleeps for 19 hours a day after being injected with swine flu vaccine.
Josh Hadfield, seven, can fall asleep every five minutes even when he is walking, eating and swimming.
Now his mum Caroline, 42, is taking legal action after the Health Protection Agency because she claims Josh's condition – called narcolepsy, or sleeping sickness – has been caused by the anti-swine flu drug Pandemrix.
Josh received the vaccine at his local GP surgery on January 21, 2010, after Caroline was told he was vulnerable to the H1N1 virus because he was under five.
But Caroline, of Frome, Somerset, said that within weeks of the jab she noticed a drastic change in her son.
She said: "He was a perfectly healthy energetic four-year-old before the vaccination, but within two weeks he was getting more tired and after three weeks he was sleeping for 19 hours.
"Things then developed quickly and he struggled to walk. Nothing could convince me it was anything but the jab which caused Josh's conditions," she said.
"The Government had a knee-jerk reaction to swine flu and put out this vaccine, giving it to very young children."
Josh is now on medication to control the condition but the family live in constant fear of narcolepsy attacks.
Caroline said: "Laughter can trigger attacks and Josh was too anxious about fear of an incident to go sledging in last week's snow.
"You see other children who can laugh and enjoy things and, yes, Josh can laugh and enjoy things but his reaction means that he goes unconscious. We feel we are constantly treading on eggshells."
The vaccine was widely used in the UK during the 2009-2010 flu pandemic and given to almost one million children between the ages of six months and five years.
However, following a number of trials across the EU, it is no longer in use after links between the drug and narcolepsy were found in youngsters from Finland, Sweden and Ireland.
Caroline and Josh's dad Charlie, 47, a printer, have joined a group of other parents preparing legal action after their children developed similar symptoms.
But the Department of Work and Pensions, which is responsible for administering the Vaccine Payments Scheme, said there is currently insufficient medical evidence to show that the swine flu vaccine causes narcolepsy.
Caroline insisted that the HPA report was a huge leap forward and she did not know how the Government could ignore it.
She added: "That is the first report I have seen that has been published which shows that there is a ten to 16-fold increase in cases since the vaccines was given.
"That is a huge, huge, leap forward and I can't really see now how the Government can turn around and say that there's no link because obviously there is."
A spokesman for GlaxoSmithKline, the pharmaceutical company which produced the drug, said: "Narcolepsy is a complex disease and its causes are not yet fully understood but it is generally considered to be associated with genetic and environmental factors, including infections.
"It is crucial we learn more about how narcolepsy is triggered and how Pandemrix may have interacted with other risk factors in affected individuals."