You're a nurse. You speak the language of biology. You've sat in on rounds, you've read the charts, you've probably even heard the words "chemical imbalance" used as a neat, tidy explanation for a patient's profound, messy pain.

It's a clean diagnosis. It's simple. It's biological. It fits on a chart.

And now, as you navigate the crushing, complicated weight of your own burnout and grief, you find yourself applying that same diagnosis to yourself. My brain must be broken. My serotonin must be low. This exhaustion, this sadness… it's a chemical defect. I just need the right medication to fix it.

What if the diagnosis itself is the sickness? What if it's a marketing slogan that has been holding millions of us hostage for decades?

The Takedown: A Scientific Reckoning

For over 30 years, the "serotonin theory of depression" has been treated as gospel. And for over 30 years, there has been a profound lack of definitive evidence to support it.

In 2022, a team of researchers led by Dr. Joanna Moncrieff published a massive "umbrella review" in the journal Molecular Psychiatry. This wasn't just another study. It was a comprehensive review of decades of research involving more than 160,000 participants. It found no consistent support for the chemical-imbalance story.

Their findings:

  • No difference in serotonin levels between depressed and non-depressed people.

  • Artificially lowering serotonin in healthy volunteers did not cause depression.

  • Even studies looking at gene variations, including the serotonin transporter gene (5-HTTLPR), showed no consistent link to depression.

The central, foundational idea that you have been sold about your own brain — that your sadness is a serotonin deficit — is not supported by the science. It was a hypothesis that failed to stand up to scrutiny, but it was kept alive by a pharmaceutical industry because it was a simple, profitable story.

But Wait — Serotonin Does Something, Right?

Yes. Serotonin is a real neurotransmitter that does many real things.

The entire mythology was built on a single, simple narrative — "low serotonin = sad" — when the real neuroscience is more complex.

The Real Story: Your Body is Keeping Score

So if it's not a chemical imbalance, what is it?

Your brain and body are a perfectly logical system that is responding to the data of your life.

The burnout you feel isn't a random serotonin dip. It's the predictable, biological consequence of the chronic, sustained stress you are under. It is a full-system response:

  • Your Nervous System: Your body is likely stuck in chronic fight-or-flight or freeze — a state our work in trauma recovery is specifically designed to address.

  • Your Hormonal System: Your adrenal glands are pumping out cortisol, which profoundly impacts your mood, energy, and sleep — and chronic cortisol exposure can dysregulate the HPA axis — and stress-related epigenetic changes appear to be part of how that happens.

  • Your Immune System: Inflammation can cause depression in healthy people. The research points to a specific pathway: inflammation activates the IDO enzyme, which diverts tryptophan (serotonin's raw material) down the kynurenine pathway — lowering serotonin and producing other mood-affecting metabolites. So yes, your serotonin may be low. But it's low because you are inflamed from stress. Your body isn't making a chemical error. It's making a chemical response to an impossible life.

Your body is keeping an accurate score of the impossible load you have been forced to carry.

The Rebellion: Demand a Therapy That Honors Your Story

This is the rebellion. It is a rebellion against a pathologizing system that prefers to give you a simplistic label and a prescription rather than engage with the beautiful, messy complexity of your life.

I'm not anti-medication. Medication can be a life-saving tool, and for many people, SSRIs work — not necessarily because they "fix a chemical imbalance," but possibly through other, more complex mechanisms we're still understanding. The crime is telling you that the medication is treating a "disease" that doesn't exist, while ignoring the lived experience that does.

Stop seeing yourself as a walking chemical imbalance and start seeing yourself as a human being with a story. You are a person whose nervous system is responding logically to an impossible situation.

Demand a form of therapy that is interested in your story. Demand a clinician who will help you audit the sources of your burnout.

When you're ready to be heard: Start here →

Part of: The Science Library → | Related: The Biology of Anxiety: What a 2025 Study Found · A Guide to Burnout