How does stress affect me when I take the TOEFL

Stress is the strongest enemy for me when I take the TOEFL I think. I don’t know why but I feel so much stress whenever I take the TOEFL. I think I needed a high score on that test to get the requirement to come here from Japan. So I took this test many times; that is why I feel too much stress on that test. When I take the TOEFL, my hands get sweaty and I can’t concentrate on the TOEFL, because of the time limit. I am affected by the noise of other people’s writing, coughs, sneezes, and the sounds of a clock when I feel stress. As a result, I usually get horrible scores. I heard moderate stress improves our ability. I agree with this opinion, except on the TOEFL, because I can’t control my temper at all on the TOEFL. I believe stress makes our TOEFL score worse.