On This Page:ToggleFunctionsHow Does Serotonin Work?Low SerotoninIncreasing SerotoninToo Much Serotonin
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Serotonin is aneurotransmitterthat regulatesmood, sleep, appetite, andcognitive functions. Though primarily found in the intestines, its presence in the brain affects emotional well-being and mental health. Abnormal serotonin levels are linked to depression and anxiety.
Key Takeaways
Functions
Behavior
Serotonin is projected from thebrain stemand reaches most regions of the brain, giving it a wide array of effects on many aspects of behavior:
Mood
Serotonin is one of the key neurotransmitters involved inmodulating mood, since it:
Sleep
Physical Health
Outside of brain functions, serotonin also plays a big role inphysical health:
How Does Serotonin Work?
The scientific name for serotonin is 5-hydroxytryptamine (5-HT), a monoamine group neurotransmitter that contains amino acids.
The monoamine group ofneurotransmittersplays a role in many functions, such as decision-making, emotions, happiness, rewards, and has associations with mental health conditions as a result.
Within the brain, serotonin mostly originates in the brain stem within a cluster of nuclei called theRaphe nuclei.
Serotonergic fibersare then synthesized from the Raphe nuclei and projected to thenucleus accumbens, part of the basal forebrain that is known as the circuit area for rewards.
Here, it is then projected throughout the brain, including the lobes of the brain, hippocampus, cerebellum, and spinal cord.
Duringneurotransmission, serotonin is released into thesynaptic cleftfrom the terminals of the presynaptic neuron.
Serotonin can act as bothexcitatory and inhibitory, depending on the type of receptors it binds to and the location within the brain. Its effect is context-dependent.
In some brain regions or circuits, serotonin can increase neuronal activity (excitatory); in others, it can decrease activity (inhibitory).
Low Serotonin
In regard to serotonin within the brain, there are many symptoms that can be associated with low levels of this neurotransmitter:
Low levels of serotonin have been associated with some mental health conditions, such asmood disorders,anxiety disorders,and schizophrenia.
Low levels of serotonin could be due to not producing enough of this neurotransmitter. An amino acid calledtryptophanis essential for the production of serotonin.
This amino acid is only obtained from food, so if there is a deficiency of this, less serotonin will be made as a result. Similarly, vitamin B6 and D deficiencies have been linked to lower levels of serotonin.
Another cause of low serotonin levels can result from not having enoughserotonin receptorsin the brain or the receptors not functioning properly.
When serotonin leaves the presynaptic neuron, it could be broken down in the synaptic cleft too quickly or reabsorbed into the presynaptic neuron too soon, stopping it from reaching the next neurons during neurotransmission.
Increasing Serotonin Levels
Increasing serotonin levels can enhance mood, alleviate depression, and regulate sleep and appetite. Proper serotonin balance is essential for emotional and mental well-being.
While medications are often prescribed to treat symptoms associated with low serotonin, there are alsonatural waysto boost serotonin levels:
Medications
Tricyclic antidepressants (TCAs) and Monoamine oxidase inhibitors (MAOIs):Older classes of antidepressants that also increase serotonin levels, but with more side effects compared to SSRIs.
While medications can be effective for treating serotonin imbalances, it’s important to work with a healthcare provider to find the right treatment plan.
Incorporating natural methods to boost serotonin, alongside medical treatment when necessary, can help promote overall emotional well-being.
Too Much Serotonin
Although serotonin is beneficial in maintaining a good mood and providing people with happy feelings,too much serotonin can be detrimental.
A surplus of serotonin in the brain can be a result of the medications that are being taken to increase low serotonin levels.
Too much serotonin in the brain can result in a condition calledserotonin syndrome.
This syndrome can arise after starting to take a new medication, or when increasing the dosage of an existing medication.
Some of the milder symptoms associated with serotonin syndrome are as follows:
Mild cases of serotonin syndrome may go away within a day of stopping the medications causing the symptoms, although if not treated it could result in worsened symptoms such as seizures, irregular heartbeat, unconsciousness, or even death in the worse cases.
Therefore, if someone is considering taking medication for curing symptoms of low serotonin or associated mental health conditions, they would be advised to start with a small dosage before potentially increasing this.
References
Berger, M., Gray, J. A., & Roth, B. L. (2009). The expanded biology of serotonin.Annual review of medicine, 60, 355-366.
Lane, R., Baldwin, D., & Preskorn, S. (1995). The SSRIs: advantages, disadvantages and differences.Journal of psychopharmacology, 9(2_suppl), 163-178.
Mayo Clinic. (2019, October 8).Tricyclic antidepressants and tetracyclic antidepressants. https://www.mayoclinic.org/diseases-conditions/depression/in-depth/antidepressants/art-20046983
Further ReadingOlivier B. Serotonin: A never-ending story. European Journal of Pharmacology. 2015;753:2-18.Harmer, C. J., Duman, R. S., & Cowen, P. J. (2017). How do antidepressants work? New perspectives for refining future treatment approaches. The Lancet Psychiatry, 4(5), 409-418.Cowen, P. J., & Browning, M. (2015). What has serotonin to do with depression?. World Psychiatry, 14(2), 158.Lin, S. H., Lee, L. T., & Yang, Y. K. (2014). Serotonin and mental disorders: a concise review on molecular neuroimaging evidence. Clinical Psychopharmacology and Neuroscience, 12(3), 196.Banskota, S., Ghia, J. E., & Khan, W. I. (2019). Serotonin in the gut: Blessing or a curse. Biochimie, 161, 56-64.
Further Reading
Olivier B. Serotonin: A never-ending story. European Journal of Pharmacology. 2015;753:2-18.Harmer, C. J., Duman, R. S., & Cowen, P. J. (2017). How do antidepressants work? New perspectives for refining future treatment approaches. The Lancet Psychiatry, 4(5), 409-418.Cowen, P. J., & Browning, M. (2015). What has serotonin to do with depression?. World Psychiatry, 14(2), 158.Lin, S. H., Lee, L. T., & Yang, Y. K. (2014). Serotonin and mental disorders: a concise review on molecular neuroimaging evidence. Clinical Psychopharmacology and Neuroscience, 12(3), 196.Banskota, S., Ghia, J. E., & Khan, W. I. (2019). Serotonin in the gut: Blessing or a curse. Biochimie, 161, 56-64.
Olivier B. Serotonin: A never-ending story. European Journal of Pharmacology. 2015;753:2-18.
Harmer, C. J., Duman, R. S., & Cowen, P. J. (2017). How do antidepressants work? New perspectives for refining future treatment approaches. The Lancet Psychiatry, 4(5), 409-418.
Cowen, P. J., & Browning, M. (2015). What has serotonin to do with depression?. World Psychiatry, 14(2), 158.
Lin, S. H., Lee, L. T., & Yang, Y. K. (2014). Serotonin and mental disorders: a concise review on molecular neuroimaging evidence. Clinical Psychopharmacology and Neuroscience, 12(3), 196.
Banskota, S., Ghia, J. E., & Khan, W. I. (2019). Serotonin in the gut: Blessing or a curse. Biochimie, 161, 56-64.
Saul McLeod, PhD
BSc (Hons) Psychology, MRes, PhD, University of Manchester
Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.
Olivia Guy-Evans, MSc
BSc (Hons) Psychology, MSc Psychology of Education
Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.
