Have you ever noticed all the different emotions you experience in a normal day? For example, you can feel happy in the morning when you find out you passed your bio quiz, grumpy at noon when you haven’t eaten since breakfast, and then sad when the football team loses the big Homecoming game.
Chemicals called neurotransmitters, which carry messages across the gaps between neurons in your brain, influence your changing mood. One neurotransmitter, dopamine, increases alertness and makes you feel happy when something good happens. Lots of abused drugs raise a person’s level of dopamine.
Serotonin, another neurotransmitter, affects the brain in a different way. Known as the “calming chemical,” serotonin eases tension and stress. It lifts a person’s mood, lessens anxiety and aggression, promotes sleep, and also affects appetite, memory, and perceptions.
“It’s a molecule involved in helping people cope with adversity … to keep going and try to sort everything out,” says Philip J. Cowen, a serotonin expert at Oxford University and the Medical Research Council. To quote his Manchester University colleague Bill Deakin, “It’s the ‘Don’t panic yet’ neurotransmitter.”
Serotonin also puts a brake on the excitement and sometimes recklessness that dopamine can produce. When the overall brain chemical system is working well, it seems that these chemicals interact to balance out extreme behaviors. That’s why it can lead to problems when a person takes illegal drugs that affect serotonin or dopamine.
Many different drugs affect serotonin levels in complex ways. For example, when a person uses MDMA (Ecstasy or “Molly”), serotonin increases in different parts of the brain, causing elevated mood and feelings of empathy. Some studies show that elevated serotonin from illegal drug use plays a role in the person wanting to take more of the drug, possibly leading to addiction.
For more information on how drugs affect brain chemicals, check out NIDA’s article, Impacts of Drugs on Neurotransmission.