Sarah Elizabeth suffers from narcolepsy, which is a sleep disorder characterized by a loss of control over your sleep-wake cycles. Narcoleptics may feel constantly sleepy, and they can also experience sleep attacks where they spontaneously fall asleep for a period of a few seconds to several minutes. Sarah also suffers from cataplexy, a condition which causes sudden loss of muscle control and renders the sufferer unable to move.
"It can be very frustrating to try to explain what it's like to people who have never seen narcolepsy in real life, and how much of a struggle it can be," says Elizabeth. "Most people think that it's funny until they see what actually happens, or they are completely unprepared and get really scared and panic."
Elizabeth posted the video below, which shows her having a spontaneous attack while filming a dance routine, in order to show people what her condition is really like. "Just like people with epilepsy, I can't control having a sleep attack or cataplexy any more than they can control having a seizure."
She also did a Reddit AMA ("Ask Me Anything"), which is highly informative and can be read here.