Kleine-Levin syndrome is a rare disorder characterized by recurrent episodes of hypersomnia, hyperphagia, hypersexuality and delusion and hallucination with spontaneous recovery. A 17-year-old female suddenly showed hypersomnia, severe fatigue, and compulsive hyperphagia. She was diagnosed with suspected Kleine-Levin Syndrome. The precipitating factor was an upper respiratory tract infection that the patient had undergone 2 weeks prior. Past psychiatric history included somnambulism and ADHD; her symptoms of ADHD included attention deficit, impulsiveness, hyperactivity, and irritability. This was her third episode. Her hypersomnia was longer in duration but lower in frequency compared with usual KLS. Her low LF/HF ratio in heart rate variability measurement showed high parasympathetic nerve activity. A MMPI report showed some psychological problem. The patient was diagnosed of gastric fever by pattern identification. Her hypersomnia episode improved 6 weeks after onset. This is the first reported case of suspected Kleine-Levin Syndrome in the field of Oriental Medicine in Korea.