Beth Goodier, of Stockport, England, was diagnosed with Kleine-Levin syndrome when she was 16 years old.
Her mom, Janine Goodier, told InsideEdition.com she had just recovered from tonsillitis when she started coming home from class complaining of extreme fatigue and inability to focus.
"She was struggling to stay awake," Goodier said. "That continued for about two weeks. One day, she fell asleep on the sofa downstairs, and didn't wake up."
Panicked, Goodier said she eventually shook her daughter awake, but as she regained consciousness, Beth started babbling incoherently, as if she were a child again.
Beth was taken to the hospital, where she remained for the first several months on and off, until a neurologist recognized the symptoms and diagnosed her with KLS.
Although seven years have passed since her diagnosis, "It's never nice. My heart always sinks, but it is what it is. We have to get on and cope with it," her mom said.
Goodier explained when Beth is awake, anywhere between two and six hours a day, her 22-year-old daughter reverts back to her 5-year-old self when she is "asleep." Beth is often confused and frustrated by the world around her. She often asks, "Am I dead, mummy?" and speaks in a child-like voice.
When Beth wakes up, she has no recollection of the episode. Her mom spends the first few moments catching her up on major events. She has compared it to losing portions of her life.
"She doesn't remember her 17th year at all, and she probably won't remember much of this year either," Goodier said. Beth is currently "asleep," and has been for the last two and a half months.
While Goodier has since started recognizing signs that her daughter will fall into another episode, including exhaustion and a poor mood, the time frame for each episode tends to be unpredictable. They can last as long as several months, or as short as a little over a week, while her good days can range from a few weeks, to just a few days.
But when she's "awake," she likes exercising to offset the binge eating typical of her episodes, and putting together video blogs to give viewers a glimpse into her world.
"I wanted to show people what my life was like," Beth said in one of her vlogs, which discuss topics from mental breakdowns to sweet moments with her boyfriend, Dan.
Beth and Dan, 25, met three years ago, and he has been patient with her illness ever since they got together.
However, her mom said she often thinks about the rest of her life that she has missed out on. She stopped attending school soon after her diagnosis, and is unable to work because of her unpredictable schedule.
"Maintaining friendships is very difficult as well," her mom explained. "They forget about her. They're all going off to [college] and it's difficult. She should be the one doing it but she can't."
According to doctors, people often get KLS in their youth years, and grow out of it in an average of 13 years. But because the disease is so rare, most people go several years before they are diagnosed.
Goodier added that doctors expect Beth to take longer to grow out of it since her episodes are so severe.
"My heart goes out to everyone with KLS, especially my daughter," Goodier told InsideEdition.com. "I'm very proud of her."