"It might sound funny to others, but suddenly thinking you are French is terrifying," says Louise Clark who was recently diagnosed with a very rare brain disorder.
Susac's Syndrome is brought on by stress and affects the brain, ears and eyes, mainly in young women.
As Miss Clarke's case shows, it can also make the sufferer think they are living in a memory of something they experienced months or years earlier.
The woman who woke up thinking she was French