Whenever you suffer from higher than normal levels of stress your body goes through a "flight or fight" response. During this stage your mind requires more than normal levels of hormone just in case you are pushed into a situation that you need extra levels of energy and power. This process releases more hormones from your androgen gland however when this increase in hormone levels occur, you are releasing more sebum, which is the hormone responsible for blocking follicles and clogging pores. Clogged pores leads to bacteria and oil build up which starts the development of acne.