Every seven months, female student Lily Clarke sleeps continuously for up to two months.
The Sun reported that the girl, who suffers from the rare Kleine-Levin Syndrome, has slept through exams, Christmas and New Year.
Her mother, Adele, 47, said that she is missing out on a large part of her life as a result of her condition which started in 2007.
There is no known cure for Kleine-Levin Syndrome.
The family had gone for food after an ice-skating session and Lily fell asleep even before the food arrived. She could not be awakened and her family members who had to carry her from the restaurant.
She later woke up for a short while, which allowed enough time for her parents to feed her.
Medical practitioners believe that the condition affects young people, which means that Lily may grow out of it eventually.