What does serotonin do?

“I keep hearing about serotonin but what does it do?”

Serotonin is a complex substance found in the brain and body that acts as a neurotransmitter that has its "fingers" in many body functions. It helps transport information across the synapse, or space between neurons. Then it is recollected and stored for when the next transport is required. Serotonin helps to modulate one’s mood, impacts cognition or thinking, the brain’s reward system, memory, and many physiological processes such as vomiting. When it migrates from tissue cells into the blood, the platelets pick up the serotonin and store it. When the platelets bind to a blood clot, they release serotonin, where it can serve either as a constrictor or a dilator of blood vessels, depending on what is required. Serotonin also serves as a growth factor for some types of cells that may assist in wound healing. In balance, its functions are quite amazing. Out of balance—too high or too low—is an entirely different story.