Which neurotransmitter is known for regulating hunger, sleep, arousal, and mood?

The neurotransmitter that plays a prominent role in regulating hunger, sleep, arousal, and mood is serotonin. This chemical messenger is crucial in various physiological functions, including mood stabilization and emotional well-being. It is heavily involved in the regulation of appetite, as it can influence feelings of satiety and hunger. Additionally, serotonin affects sleep patterns, as it helps regulate the sleep-wake cycle, making it integral to sleep quality and duration. Its influence on arousal is connected to its overall impact on mood and emotional regulation, enhancing feelings of happiness and well-being. Research has established links between serotonin levels and various mood disorders, highlighting its significance in both emotional and physical health.

In contrast, the other neurotransmitters have distinct roles: dopamine primarily relates to pleasure and reward mechanisms, GABA serves as the main inhibitory neurotransmitter in the brain, helping to calm neural activity, and norepinephrine is more closely associated with the body's stress response and alertness rather than the functions mentioned in the question. Thus, serotonin is the primary neurotransmitter that encompasses the regulation of hunger, sleep, arousal, and mood.