Which neurotransmitter is primarily involved in mood, sleep, and appetite?

• A. Dopamine
• B. Serotonin
• C. Norepinephrine
• D. Acetylcholine

Answer: (B)

Serotonin is the neurotransmitter that helps regulate mood, sleep, and appetite. It influences how we feel emotionally and how we respond to stress, with lower levels often linked to depressed mood. It also affects the sleep–wake cycle; serotonin is involved in signaling the transition between wakefulness and sleep and, in the pineal gland, helps regulate melatonin production for nighttime signaling. In terms of appetite, serotonin helps signal fullness and satiety, contributing to when we stop eating. These broad roles make serotonin the best match for mood, sleep, and appetite.

Dopamine is more tied to reward, motivation, and movement; norepinephrine is linked to arousal and alertness; acetylcholine is important for memory and learning.