Communication apprehension is defined as fear, anxiety, or nervousness connected to real or anticipated communication. Physical symptoms of communication apprehension, or "stage fright", include sweaty hands, flushed cheeks, rapid heart rate, and nausea. The body's release of adrenaline in stressful situations helps increase performance but can also restrict pain receptors. Causes of communication apprehension include past negative experiences, uncertainty about an experience, concern about impacts on one's life, discomfort with attention, feeling one has nothing valuable to contribute, and sensing tension in others.