According to T. Singer there are good stresses and bad stresses. We become stressed when our brain perceives a stimulus and our nervous system starts to react. Adrenal glands release the first stress hormone, epinephrine or adrenaline. This hormone dilates the bronchial tubes in the lungs, making the heart race and breathing more difficult. Blood flows quickly to the brain and the muscles. This activates the fight or flight reflex. The next stress hormone, cortisol, is then triggered. When we know that the event will end, such as riding a roller coaster or watching a scary movie, cortisol can be good. It gives us energy for the duration of the stressful event. When the stress doesn’t end, and the cortisol continues to be produced, it can be dangerous.