Medically reviewed by Rachel Goldman, PhD, FTOS Key Takeaways Serotonin is a neurotransmitter important for mood, digestion, and sleep.You can increase serotonin levels naturally through exercise and ...

Dopamine is the neurotransmitter everyone has heard of. Dopamine existed long—I mean really long—before there were humans. It can be traced back at least 600 million years in the history of life, ...