Cataplexy is an episodic condition featuring loss of muscle function, ranging from slight weakness such as limpness at the neck or knees, sagging facial muscles,[22] weakness at the knees (often referred to as "knee buckling"),[23] or inability to speak clearly, to a complete body collapse.[22] Episodes may be triggered by sudden emotional reactions such as laughter, anger, surprise, or fear, and may last from a few seconds to several minutes. The person remains conscious throughout the episode. In some cases, cataplexy may resemble epileptic seizures.[22] Usually speech is slurred and vision is impaired (double vision, inability to focus), but hearing and awareness remain normal. Cataplexy also has a severe emotional impact on narcoleptics, as it can cause extreme anxiety, fear, and avoidance of people or situations that might elicit an attack