What is the primary role of serotonin in the human body?

• A. Regulates respiration
• B. Regulates digestion
• C. Regulates mood, appetite, and sleep
• D. Regulates heart rate

Answer: (C)

Serotonin plays a crucial role in regulating mood, appetite, and sleep, making it a key neurotransmitter in the central nervous system. Its influence on mood is particularly significant, as low levels of serotonin are often associated with feelings of depression and anxiety. By helping to modulate these emotional states, serotonin contributes to overall mental well-being. Additionally, serotonin affects appetite by signaling to the brain when hunger or satiety should occur, and it is also involved in sleep regulation by influencing the sleep-wake cycle and contributing to the quality of sleep.

This central role in mood, appetite, and sleep distinguishes serotonin from the responsibilities associated with other options. For instance, while serotonin has some effects on digestion, its primary functions relate more to the emotional and behavioral aspects of health rather than merely regulating digestive processes or respiratory functions.