Epinephrine, also known as adrenaline, is a neurotransmitter and hormone essential to metabolism. It regulates attention, mental focus, arousal and cognition. It also inhibits insulin excretion and raises the amounts of fatty acids in the blood. Epinephrine is made from norepinephrine and is released from the adrenal glands. Low levels can result in fatigue, lack of focus and difficulty losing weight. High levels have been linked to sleep problems, anxiety and ADHD.