Adrenaline or epinephrine is a hormone and neurotransmitter produced in the adrenal gland. It is produced by the body in response to fear, anxiety, stress or other intense emotion. Adrenaline has the effect of allowing the body to increase its uptake of sugar to the cells, which has the effect of raising the heart rate, increasing respiration, and making the body less sensitive to pain. In normal circumstances, this makes the human body stronger and faster for short periods of time so that it can respond to dangerous situations. However, long term exposure to adrenaline, such as that which results from stress, can lead to strain on the heart and lungs, as well as secondary symptoms such as insomnia and irritability.