Narcolepsy is a serious disorder in which people may randomly fall into a deep sleep, right into the REM stage of sleep in fact. This sleep may last a few minutes or a couple of hours and, often, vivid hallucinations occur. It is usually brought on by strong emotions and orexin plays a strong role in narcolepsy. Victims of narcolepsy usually experience cataplexy, or the loss of muscle tone, before they fall into their deep sleeps.
Recent studies have shown a tie between the H1N1 vaccines that carry pandemrix and increased chance of narcolepsy, especially in Finland. Children between 4 and 12 who have received the vaccine are 13 times more likely to develop narcolepsy. Pandemrix is used primarily to prevent swine flu and, for the most part, its positive side effects out weigh the negative ones. The exact effects of pandemrix on narcolepsy are not completely understood, currently. Right now, we know that pandemrix is an immunologic adjuvant, meaning that it increases the immune systems response to vaccines.
Tests are currently being done to see how pandemrix effects narcolepsy but they are hard to recreate since people will not be involved in them, so past patients is the most effective way to study this. However, this data will probably not produce an accurate cause and effect relationship. Whether or not pandemrix causes an increase in narcolepsy is unclear as well. Other parts of the H1N1 vaccine might be the causes but only tests and scientific thinking will tell. In summary, we do not know if we can rule out other possible hypothesis, how replicable this experiment would be and if pandemrix actually causes narcolepsy directly or if it triggers something that brings on narcolepsy. Only time will tell what effect pandemrix has on narcolepsy but it is currently unclear and intriguing.
http://www.thl.fi/en_US/web/en/pressrelease?id=26352
http://www.bbc.co.uk/news/uk-northern-ireland-15130951
The BBC link you provided isn't working anymore, but the other one is dense with interesting statistics. I always read these sorts of claims with skepticism. High profile cases have been based on claims that breast cancer is caused by electrical power lines, uterine cancer is caused by IUDs, autism is caused by childhood vaccinations....yet all have been found to be illusory correlations.
The other interesting angle to a report like this is inference. Let's say that this time there is a real relationship between narcolepsy and the pandemrix vaccine. Should we stop using pandemrix?
This is where I find base rates so important.
In Finland the increased risk of narcolepsy was 6 per 100,000 cases. To make sense of that, you need the comparison, what is the risk of dying from Swine Flu? The article talks around this but doesn't provide the answer. The vaccine prevented 40,000 cases of swine flu, but that isn't the same. It's so important to get your numbers lined up so decision makers can compare, and this article, with all its numbers, doesn't provide that!