Which neurotransmitter or hormone affects eating and alertness?

Norepinephrine is a neurotransmitter and hormone that plays a crucial role in the body’s response to stress and alertness, particularly in the brain. It is part of the sympathetic nervous system, which is responsible for the fight-or-flight response. When released, norepinephrine increases arousal and alertness, enhancing focus and attention. Additionally, norepinephrine influences appetite regulation; its levels can impact eating behavior, often suppressing hunger as part of the body’s stress response.

Other options do not have the same dual role in affecting both eating and alertness. While ADH (Antidiuretic Hormone) primarily regulates water balance and kidney function, acetylcholine is mainly involved in muscle activation and functions in the parasympathetic nervous system rather than directly influencing appetite and alertness. Oxytocin is generally associated with social bonding and reproduction rather than energy balance or alertness. Therefore, norepinephrine stands out as the neurotransmitter or hormone that directly affects both eating and alertness.