when someone starts to feel the sensation of being scared or nervous they start to experience anxiety. according to a harvard mental health letter, "anxiety usually has physical symptoms that may include a racing heart, a dry mouth, a shaky voice, blushing, trembling, sweating, lightheadedness, and nausea". it triggers the body to activate its sympathetic nervous system. this process takes place when the body releases adrenaline into the blood stream causing a chain of reactions to occur. this bodily response is known as the "fight or flight" syndrome, a naturally occurring process in the body done to protect itself from harm. "the neck muscles contract, bringing the head down and shoulders up, while the back muscles draw the spine into a concave curve. this, in turn, pushes the pelvis forward and pulls the genitals up, slumping the body into a classic fetal position".