Although neuroscience is hardly an easy topic, it’s by no means a dull one. There are two main systems of magical autoregulation in our bodies: the nervous and endocrine systems. Which one is more impressive — hard to tell. The world of regulating chemicals is immense and fascinating, and it would take ages to cover it all. I won’t pretend I’d be better at explaining it than the many comprehensive and engrossing resources that already exist (see the References section). So instead of giving you excerpts from encyclopaedias and textbooks, I’d rather paint a picture.
Key characters
I don’t want to overwhelm you with unnecessary details of brain chemistry — not least because it’s not yet fully understood even by the scientists themselves. But I do think it helps to meet the main players before we see them in action.
So many of the issues that bring people to therapy — depression, anxiety, addiction, trauma, stress — are deeply intertwined. Trauma can lead to addiction later in life. Depression and anxiety often go hand in hand. And all of these are not purely “mental” problems, because the brain itself is not purely mental. It’s constantly adjusting, changing, responding to the environment, and this flexibility is underpinned by chemical processes. The chemical cocktail of anxiety looks different from that of addiction or depression. Although communication within the brain travels in circuits that involve electrical signals, those circuits are controlled chemically, and the electrical signals themselves are the result of chemical reactions. This is why understanding the key compounds matters — they shape how we think and feel.
Chemical players
It would be rather tiresome if, while making your morning cup of coffee, you also had to manually adjust your liver function and press on your chest to keep your heart pumping. Thankfully, all of this essential activity is carried out automatically. The chemicals below are the ones doing much of that invisible work — especially when it comes to mood, motivation, stress, and connection.
Oxytocin is the hormone of touch and bonding — the warm feeling when someone you love holds you close. Serotonin is your internal pressure valve; with enough of it on board, you genuinely can “work well under pressure.” Endorphins are the body’s natural painkillers — they’re released during exercise, laughter, and moments of intense emotion to help you cope. Dopamine is the engine of desire and reward; it’s what drives your goals, fuels your habits, and makes you want to repeat experiences that felt good. Cortisol is essential for waking up, learning, and problem-solving — but too much of it, for too long, becomes a slow poison. Adenosine quietly builds up throughout the day, making you progressively sleepier — the whole chemistry of waking and tiredness is fascinating in its own right. And adrenaline (epinephrine) and noradrenaline (norepinephrine) are the body’s emergency responders — they flood your system when you need to act fast.
Anatomical players
These chemicals don’t operate in a vacuum — they’re produced, regulated, and interpreted by specific structures in the brain.
The hypothalamus is the bridge between the brain’s control room (the nervous system) and the endocrine system, which communicates with the rest of the body through chemical signals and feedback loops. The hippocampus is essential for learning and memory — it helps you store what matters. The amygdala is the brain’s labelling machine: it tags experiences with emotional significance, deciding what’s dangerous, important, or worth remembering. The pituitary gland acts as the endocrine system’s master dispatcher, translating signals from the hypothalamus into hormonal instructions. The prefrontal cortex (PFC) is where planning, decision-making, and impulse control happen — the rational counterweight to the amygdala’s emotional reactions. The nucleus accumbens is at the heart of the brain’s reward circuit, processing pleasure and reinforcement. And the dorsal striatum helps turn rewarded behaviours into habits — it’s where conscious choices gradually become automatic.
There are, of course, many more chemical compounds — well-researched and those still to be understood — that shape our minds. But these are the major players we need to meet before seeing them in action.
The play
Imagine you’re on the sofa after a long day at work. You’re exhausted — the kind of tired where even reaching for the remote feels like effort. That’s adenosine doing its job, quietly accumulating throughout the day, nudging you towards rest.
Then your little one walks over, climbs up, and gives you a hug and a kiss. That warm, melting feeling — that’s oxytocin flooding in. The hormone of connection, of touch, of belonging. And the happiness that follows — that gentle glow of this is good, this is where I want to be — that’s endorphins at work, the body’s own way of rewarding you for being close to the people you love. Meanwhile, dopamine is quietly taking notes: remember this moment, remember what led to it, do it again. The more reliably something brings pleasure, and the faster it arrives, the more dopamine reinforces the pattern. That’s why, by the way, addictions are so easy to acquire and so hard to get rid of. Dopamine isn’t about long-term benefits or weighing pros and cons. It’s purely about incessantly seeking short-term rewards.
Now imagine a loud bang outside — sharp, sudden, unexpected. Your heart rate soars. You’re on your feet before you’ve even thought about it. That’s adrenaline surging through your system, putting your body on high alert in a fraction of a second. And the oxytocin? It’s still there — but now it’s showing its other face. The same hormone that made you melt into a hug is now making you fiercely protective. Anything that threatens your family triggers that primal, aggressive edge. Cortisol kicks in too, mobilising energy reserves you didn’t know you had after such a long day — sharpening your focus, preparing you to act.
This is the orchestra of your nervous system. The same chemicals that help you love are the ones that help you fight. The same ones that help you learn are the ones that keep you awake at night when something’s wrong. Understanding them doesn’t take away their magic — it helps you recognise what your body is already telling you.
The rest of this section is coming soon — we’ll explore what happens when these systems get stuck, and what therapy can do about it.