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How Do Thumb and Finger Sucking Affect Neurotransmitters?

While most parents are aware that infants and toddlers find thumb- and finger-sucking comforting, most explanations don’t go beyond the idea of recreating the comfort of feeding from a breast or bottle. It turns out there may be more to it than that. This article discusses how thumb- and finger-sucking can affect our neurotransmitters. Keep reading to learn more.

Brain Chemistry

Thumb- and finger-sucking trigger the release of serotonin, dopamine, and endorphins in the brain. These neurotransmitters attach to areas of the brain, literally opioid receptors, that govern pleasure. The substance or activity that triggers the release can become addictive as the person seeks to repeat that pleasurable sensation.


Serotonin is a neurotransmitter that also acts as a hormone. Most of it resides in the gut, but about 10% of its production is in the brain. Serotonin affects mood, sleep, appetite, digestion, and more. People diagnosed with depression sometimes take serotonin reuptake inhibitors (SSRIs) to allow more of the chemical to circulate in the brain and boost their mood.


Dopamine is another “feel good” brain chemical. It partners with serotonin to regulate sleep but also has independent functions. Dopamine releases when you expect a reward and thus plays a role in motivation. When you’ve met a goal or accomplished a task, dopamine helps you feel good about it.

Dopamine primarily resides in the brain, affecting hunger (upping it, where serotonin suppresses it), mood, memory, attention, and movement. The “high” that a surge of dopamine creates result from many different pleasures, from good food to good sex to consuming alcohol. Craving that pleasurable surge may play a role in addictions to drugs, alcohol, or sex. We return to behaviors, some damaging, that create an intensely pleasurable feeling.


Produced in the pituitary gland and hypothalamus within the brain, endorphins are a group of more than 20 neurotransmitters that form a natural response to pain. The name of these chemicals comes from a combination of the words “endogenous,” meaning within the body, and “morphine,” the pain reliever.

Endorphins are the source of the “runner’s high” you feel after vigorous exercise. They also may account for the giddy feeling you get when you fall in love and how laughing makes us feel.

It’s becoming apparent that thumb- and finger-sucking affect neurotransmitters in the same way as adult activities like drinking and having sex. Viewed this way, a child’s desire to engage in thumb or finger sucking is more understandable. Nevertheless, parents and pediatricians recognize the need to learn how to break the finger-sucking and thumb-sucking habits before they cause dental and other health problems. In time, kids will choose healthy activities, like playing sports, dancing, making art, or similar, when they desire the boost of happiness and security that thumb- and finger-sucking once provided.