Bella Andrew, 24, sleeps more than 20 hours a day and becomes a "zombie" during her episodes. She has had numerous episodes that lasted for weeks at a time since she was 17, but she was only diagnosed in September.
"Sleeping beauty syndrome" — medically called Klein-Lewin syndrome (KLS) — causes intermittent episodes of sleeping for long periods of time, often 16-20 hours per day, according to the Cleveland Clinic. The cause of KLS is still unknown.