Why is it so difficult to conceal nervousness? because we get so paranoid that everyone can tell because the hormone adrenaline causes a physical response because nervous people are very bad at controlling their body language because it is similar to deception?

It is difficult to conceal nervousness because the hormone adrenaline causes a physical response.

Human body's reaction to being nervous can flare up in very uncomfortable physiological ways. Sympoms include: we begin to sweat, our cheeks flush, and some of us even develop a nervous tic--a bouncing knee, twitchy foot, nail biting, blinking too rapidly, or speaking too quickly.