Adrenaline, also known as epinephrine, is a hormone and neurotransmitter that plays a key role in the body’s fight-or-flight response. Produced by the adrenal glands, it increases heart rate, dilates airways, and boosts energy during stressful or emergency situations. Rather than promoting sleep, adrenaline does the opposite — it stimulates alertness and arousal, making it difficult to rest or relax. In times of physical danger or emotional stress, adrenaline floods the bloodstream to prepare the body for action. High levels of adrenaline in the evening, often due to anxiety or overstimulation, can interfere with sleep by keeping the nervous system in an excited state. While adrenaline and melatonin both affect energy levels, their functions are entirely different — one gets you going, the other helps you wind down. For regulating sleep, melatonin is the correct answer, not adrenaline.