serotonin and depression

How Does Serotonin Affect Depression?

Dr. Jolene BrightenPublished: Last Reviewed: Anxiety, Depression, Mood Leave a Comment

You probably know serotonin best as the “happy molecule,” but how exactly is it linked to our mood? This hormone plays a role in digestion, sleep, memory, and more but is best known for its impact on regulating happiness, anxiety, and mood.

Low serotonin levels in the brain can lead to symptoms of depression, so understanding this powerful hormone is critical in protecting our mental health. Let’s explore the causes and treatments of serotonin deficiency and what links serotonin to our mood.

Depression is a very real struggle, and support is easy to reach. If you’ve found this article because you are considering self harm, call the National Suicide Prevention Lifeline at 1-800-273-8255 right now, or visit their website for free, 24/7 live chat support.

The Chemistry Of Depression

Let’s be clear– depression is more than a chemical reaction. The American Psychiatric Association states that “Psychiatric disorders result from the complex interaction of physical, psychological, and social factors and treatment may be directed toward any or all three of these areas.” That said, it’s still helpful to understand what’s going on in our brains.

There are three major neurotransmitters– molecules that help your nervous system communicate– that we know are critical for a positive mood. Dopamine, norepinephrine, and serotonin each play a role, and deficiencies in any way contribute to depression. A neurotransmitter deficiency can occur when your brain isn’t producing the amount it needs or when it isn’t efficiently using its supply.


Best known for its role in the reward system, dopamine helps our brains balance goals, rewards, and motivation. Low levels of dopamine may explain why people with depression struggle to find motivation or happiness from activities they once enjoyed. 


Also called noradrenaline, your body uses the hormone norepinephrine as part of your “fight or flight” reaction. While that might sound bad, this means that we need norepinephrine to recognize and respond to stressful situations. Low norepinephrine may lead to depression, ADHD, or low blood pressure.

Serotonin and Depression

Serotonin is the common name for 5-hydroxytryptamine (5-HT), but we know it best as “the happy molecule.” Low serotonin levels may contribute to depression, anxiety, mood disorders, insomnia, and a higher risk of suicidal thoughts. 

The medical community links low levels of serotonin to depression. But scientists can’t yet definitively say whether low serotonin causes depression or depression depletes serotonin.

Regardless, a serotonin deficiency often points towards depression, anxiety, and mood disorders. Research shows that adequate serotonin in the brain is essential in controlling our anxiety and fear responses, as well as promoting feelings of happiness.

Learn more about serotonin:

How To Increase Serotonin Levels

Serotonin Deficiency – What’s The Risk?

Does Serotonin Reduce Depression?

For those suffering from both depression and anxiety, finding ways to boost and support serotonin in the brain may often (though not always) help alleviate symptoms. 

Serotonin is involved in mood, sleep, and digestion, all states that signal to your body, “I’m somewhere safe.” Research shows that high serotonin levels in the brain tend to correspond to happier emotions. In contrast, low serotonin levels, or fewer functioning serotonin receptors, may be linked to lower moods and symptoms of depression. 

This is why many pharmaceutical depression treatments typically revolve around promoting or recycling serotonin. Like depression itself, however, depression treatments are not one-size-fits-all. 

What Causes Changes In Serotonin Levels?

One of the best ways to increase serotonin is to identify what could be depleting it in the first place. In fact, addressing what is causing the low serotonin is essential to remedying the situation.

Inflammation, hormonal imbalances, and excessive stress can all have a negative impact on serotonin production. High alcohol intake, or a lack of sunshine are also factors that can cause a dip in serotonin.

A serotonin-deficient state doesn’t always mean that serotonin is low. Similar symptoms can also appear when your body produces enough serotonin, but isn’t using it properly. This occurs when your brain has too few serotonin receptors, or when serotonin is being stored or broken down too quickly.

One example may be seasonal affective disorder (SAD). Many people, particularly in areas with longer, darker winters, experience a seasonal depression as sunlit hours drop towards winter. While people with SAD may still be producing adequate serotonin, research suggests their brains overproduce the protein responsible for storing serotonin away and out of the active neuron synapses.

Explore more: Serotonin Deficiency, What’s the Risk?

Serotonin In Depression Treatments

One of the most common pharmaceutical treatments for depression is the use of SSRIs, or selective serotonin reuptake inhibitors. Serotonin in the brain is released and received by different neurons, acting like a messenger in the “synapse,” the space between neurons. After the serotonin molecule has delivered its message, it is reabsorbed. An SSRI acts by preventing this reabsorption so that the serotonin remains in the active synapse area and can be used over and over. Similarly, SNRIs (serotonin and norepinephrine reuptake inhibitors) reduce the reabsorption of both serotonin and norepinephrine.

Common SSRIs:

  • Prozac®
  • Celexa®
  • Zoloft.®

Common SNRIs:

  • Pristiq®
  • Cymbalta®
  • Savella®
  • Effexor.®

While your doctor can help you decide if an SSRI is the right fit for your needs, the long-term use of SSRIs can make serotonin deficiencies even worse. Additionally, while SSRIs can reduce depression symptoms by increasing serotonin availability, they don’t address the root cause of low serotonin levels.

Lifestyle changes such as sunlight, stress management, and exercise can also be potent paths to boost your body’s natural serotonin gently. Read my article on increasing serotonin levels through lifestyle, diet, and medicine.

Many of the nutrition and lifestyle approaches can be used along with an SSRI, but of course, always check with your provider.

If you are on an SSRI or SNRI and wish to stop,
you must absolutely bring this up with your prescribing doctor and adhere to their guidance on dosage. The side effects of stopping SSRIs abruptly can be brutal and dangerous, and this isn’t something you can always power through. You can avoid a lot of suffering and side effects if your doctor is keeping a close eye on your dosage adjustments and symptoms. 


Scientists are still working to understand the complex interactions between our brains and our moods, and future therapeutics could focus more on the ratios of neurotransmitters or other factors entirely. Still, understanding serotonin can be a powerful tool in understanding our mental health.

Curious about your serotonin levels? Learn more about supporting your serotonin production in this article

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  1. Pies, RW. Debunking the Two Chemical Imbalance Myths, Again. Psychiatric Times. 2019. 36.
  2. Tye, K., Mirzabekov, J., Warden, M. et al. Dopamine neurons modulate neural encoding and expression of depression-related behaviour. Nature. 2013. 493. 537-541.
  3. Hormone Health Network. Norepinephrine.
  4. Waider J. Popp S. Milnar B. et al. Serotonin Deficiency Increases Context-Dependent Fear Learning Through Modulation of Hippocampal Activity. Frontiers in Neuroscience: Neuropharmacology. 2019.
  5. Loonen AJ, Ivanova SA. Circuits Regulating Pleasure and Happiness-Mechanisms of Depression. Front Hum Neurosci. Front Hum Neurosci. 2016. 10. 571.
  6. Tafet GE, Idoyaga-Vargas VP, Abulafia DP, et al. Correlation between cortisol level and serotonin uptake in patients with chronic stress and depression. Cogn Affect Behav Neurosci. 2001. 1. 388-393.
  7. Badawy AA. Alcohol and violence and the possible role of serotonin. Crim Behav Ment Health. 2013. 13. 31-44.
  8. Sansone RA, Sansone LA. Sunshine, serotonin, and skin: a partial explanation for seasonal patterns in psychopathology?. Innov Clin Neurosci. 2013. 10. 20-24.
  9. Mc Mahon B, Andersen SB, Madsen MK, et al. Seasonal difference in brain serotonin transporter binding predicts symptom severity in patients with seasonal affective disorder. Brain. 2016. 139. 1605-1614.
  10. Siesser WB, Sachs BD, Ramsey AJ, et al. Chronic SSRI treatment exacerbates serotonin deficiency in humanized Tph2 mutant mice. ACS Chem Neurosci. 2013. 4. 84-88.
About The Author

Dr. Jolene Brighten

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Dr. Jolene Brighten, NMD, is a women’s hormone expert and prominent leader in women’s medicine. As a licensed naturopathic physician who is board certified in naturopathic endocrinology, she takes an integrative approach in her clinical practice. A fierce patient advocate and completely dedicated to uncovering the root cause of hormonal imbalances, Dr. Brighten empowers women worldwide to take control of their health and their hormones. She is the best selling author of Beyond the Pill and Healing Your Body Naturally After Childbirth. Dr. Brighten is an international speaker, clinical educator, medical advisor within the tech community, and considered a leading authority on women’s health. She is a member of the MindBodyGreen Collective and a faculty member for the American Academy of Anti Aging Medicine. Her work has been featured in the New York Post, Forbes, Cosmopolitan, Huffington Post, Bustle, The Guardian, Sports Illustrated, Elle, and ABC News. Read more about me here.