The hidden brain chemistry behind that wired-but-exhausted feeling, night-time cravings, and a nervous system that simply won’t switch off.
“She’s exhausted by 3pm. By 9pm she’s lying in bed, wide awake, replaying the day’s conversations. She reaches for chocolate or a glass of wine — not because she’s weak-willed, but because her body is desperately searching for something it’s running low in. She snaps at her family and immediately feels guilty. She wonders what’s wrong with her.”
Nothing is wrong with her.
Her nervous system has lost its braking system. And there’s a very real, very physiological reason why.
Does This Sound Like You?
If you’re nodding along to any of the following, I want you to keep reading. Because what you’re experiencing is not a character flaw, a lack of willpower, or proof that you’re “not coping.”
- You can’t switch your brain off at night, even when you’re bone tired
- You feel constantly ‘on edge’ but can’t pinpoint exactly why
- Small things feel overwhelming — noise, demands, decisions, even your phone
- You crave wine, chocolate, or carbs in the evening
- You feel anxious for no clear reason
- You wake between 2–4 am, and your mind immediately starts racing
- You feel emotionally raw or reactive in a way that isn’t ‘you’
- You’re exhausted, but sleep doesn’t restore you
- You feel overstimulated by everything and everyone by the end of the day
This constellation of symptoms could be thought of as a nervous system that’s ‘lost its brakes.’
And when I investigate the biochemistry underlying it — which I have been doing for nearly 30 years — one piece keeps coming up again and again, particularly among women navigating midlife.
……..Low GABA.
What Is GABA, and Why Haven’t You Heard of It?
Most people have heard of the neurotransmitters (brain chemicals) – serotonin and dopamine.
GABA (gamma-aminobutyric acid) gets far less attention, but it’s arguably the most important calming chemical in your brain.
GABA is your brain’s primary inhibitory neurotransmitter.
Its job is to slow things down. It’s the ‘off’ switch for an overactivated nervous system.
It quiets the constant mental chatter, eases the hypervigilance, takes the volume down on a world that feels too loud.
Think of your nervous system as a car. You need both an accelerator and brakes.
Stress hormones like cortisol and adrenaline hit the accelerator. GABA is the brake pedal. When GABA is low, you’re driving without the ability to slow down.
GABA doesn’t make you feel calm.
It allows you to feel calm. There’s an important difference.
When GABA is functioning well, you can move from stress to rest. You can lie down and actually switch off. You can handle the noise without feeling like your skin is crawling.
When it drops — and for many midlife women it does — that capacity quietly disappears.
Why GABA Drops in Midlife Women
This is where the biochemistry gets really interesting — and where it explains so much of what you’re experiencing.
1. Chronic Stress Depletes Your Natural GABA Production
When you’re under sustained stress — the relentless, low-grade kind that doesn’t end, not the dramatic kind — cortisol remains persistently elevated.
High cortisol directly inhibits GABA activity.
Your brain gets stuck in a state of high alert because the very chemistry that should be turning it off has been suppressed.
The cruel irony?
The more stressed you are, the less GABA you produce.
The less GABA you have, the harder it is to feel safe enough to rest.
The harder it is to rest, the more your stress hormones rise.
And round it goes.
2. Progesterone Is GABA’s Best Friend — and It’s Declining
This is the piece that makes perimenopause so physiologically brutal for so many women, yet almost never gets explained. Progesterone converts in the brain into a compound called allopregnanolone. Allopregnanolone is one of the most potent natural activators of GABA receptors in the body.
In simpler terms: your progesterone was quietly keeping your GABA system switched on.
As progesterone begins declining in perimenopause — often from the mid-to-late 30s, long before periods change — that GABA activation starts to fall away with it. The anxiety that seems to come from nowhere in your 40s. The sleep that was fine until suddenly it wasn’t. The sense that your emotional baseline has shifted.
This is a significant part of what’s driving it.
This is not a mental health issue.
This is a hormone neurotransmitter interaction that your body has relied on for decades, now changing.
3. Your Gut Microbiome Plays a Bigger Role Than You Think
A substantial amount of GABA is produced in the gut by specific strains of beneficial bacteria. When the gut microbiome is compromised — through antibiotic use, a processed diet, chronic stress, or digestive conditions — GABA production drops at its source.
This is one of the reasons I rarely look at anxiety, sleep issues, or nervous system dysregulation in isolation from gut function. The two systems are intimately connected through the gut-brain axis, and supporting one almost always requires addressing the other.
4. Blood Sugar Instability Hijacks Your Nervous System
When blood sugar drops — which happens with skipped meals, high-sugar diets, too much caffeine, or not enough protein — your adrenal glands release cortisol and adrenaline to compensate. This is your body’s emergency response.
The problem is, this emergency response feels identical to anxiety. Your heart rate rises, your thoughts race, your body tenses. And it further suppresses GABA activity, keeping your nervous system locked in high-alert mode.
It’s also why that mid-morning crash, the 3pm slump, and the desperate need for something sweet or starchy by evening aren’t about willpower. They’re your body trying to regulate blood sugar — and with it, your nervous system.
5. Magnesium and B6 Are the Building Blocks of GABA
GABA synthesis depends on specific nutrients — particularly magnesium and vitamin B6. These are also two of the nutrients most commonly depleted by chronic stress.
Magnesium is involved in more than 300 enzymatic reactions in the body and is rapidly excreted during stress.
If you feel that your sleep, muscle tension, and anxiety worsened during a particularly stressful period, this is part of the reason. Your body was burning through its magnesium reserves.
Why You Reach for Wine, Chocolate, and Carbs at Night
This is one of the most important things I want you to understand, because so much unnecessary guilt gets attached to it.
Alcohol activates GABA receptors in the brain. That’s why it makes you feel temporarily calmer and more relaxed. Your body isn’t craving alcohol — it’s craving the GABA activation that alcohol temporarily provides.
Similarly, sugar and refined carbohydrates cause a rapid rise in blood glucose, which triggers a brief release of dopamine and temporarily quiets the stress response.
Chocolate contains compounds that interact with GABA and serotonin pathways. These are not random cravings. They are intelligent, if short-sighted, self-regulation attempts.
Your body is not sabotaging you.
It is trying to calm itself down with the fastest tools available to it.
The problem is that both alcohol and sugar ultimately worsen GABA function over time.
Alcohol disrupts sleep architecture, reduces GABA receptor sensitivity, and raises cortisol. Sugar destabilises blood glucose further, perpetuating the cycle.
The goal is never to shame yourself for these patterns. The goal is to address the underlying GABA deficit so the cravings naturally diminish — because they no longer need to be there.
Overstimulated, Reactive, and Running on Empty
One of the symptoms my clients describe most consistently — and find most distressing because it feels so out of character — is sensory and emotional overwhelm.
The noise that used to be background now feels unbearable.
The demands that were manageable now feel crushing.
The patience that came naturally is suddenly gone.
Sound familiar?
GABA has a critical role in filtering sensory input. When it’s low, your brain loses its ability to prioritise and quieten incoming stimulation. Everything gets through at full volume. You become reactive rather than responsive, not because you’re failing as a person, but because your neurobiology is no longer buffering you the way it used to.
The “tired but wired” state many describe — physically exhausted, yet unable to switch off — is a hallmark of high cortisol combined with low GABA.
Your body is screaming for rest. Your nervous system doesn’t know how to get there.
What Actually Helps: A Root Cause Approach
Let me be clear here: supplementing GABA directly offers limited benefit for some people. At this stage, research can’t confirm or deny whether GABA molecules can cross the blood-brain barrier.
The real work is in restoring the conditions your body needs to produce and use GABA properly.
Here is where I start with clients who present with this picture:
Support GABA production through nutrients
- Magnesium glycinate or threonate — highly bioavailable forms that support both GABA synthesis and sleep quality
- Vitamin B6 (especially the active form, P-5-P) — essential for the conversion of glutamate to GABA (It is essential to check your levels before taking this)
- L-theanine — an amino acid found in green tea that enhances GABA activity without sedation
- Taurine — acts as a GABA mimetic and supports nervous system calming
Address the cortisol/GABA relationship
- Regulating blood sugar is foundational — prioritise protein at every meal, reduce refined carbohydrates, don’t skip meals
- Adaptogenic herbs such as ashwagandha and holy basil can help modulate cortisol response
- Sleep quality is both a cause and a consequence — improving sleep structure directly helps cortisol regulation the following day
Support progesterone if you’re in perimenopause
This is where working with a practitioner becomes genuinely important.
Progesterone support — whether through herbal medicine, targeted nutritional support, or bioidentical hormones where appropriate — can have a profound effect on GABA function, sleep, and emotional resilience.
This is not an area to self-manage without clinical guidance.
Prioritise gut health
There’s a reason I rarely look at nervous system symptoms in isolation from gut function.
A significant amount of GABA is produced in the gut by specific strains of beneficial bacteria — and emerging research suggests that even supplemental GABA may work partly through the Enteric Nervous System (ENS), the vast network of neurons lining your digestive tract. It’s not called the second brain without reason.
What this means, practically, is that healing your gut also heals your nervous system. Add these to your daily eating plan:
- Fermented foods (kefir, yoghurt, kimchi, sauerkraut) — these directly support the bacterial strains responsible for GABA production
- Prebiotic fibre from vegetables and legumes — this feeds and sustains those beneficial bacteria so they can do their job
- An anti-inflammatory dietary foundation — reducing gut inflammation addresses both systems simultaneously, because a gut under fire is a nervous system under fire
Create consistent ‘nervous system downshifts’ throughout the day
Long walks. Slow breathing. Morning light before screens. A consistent wind-down routine in the evening.
These are not nice-to-haves. ……
For a depleted GABA system, they are physiologically important signals that it is safe to slow down.
This Is Not Who You Are — It’s What Your Body Is Missing
If you have recognised yourself in this article, I want you to take something away from it that has nothing to do with supplements or protocols.
You are not too sensitive. You are not failing to cope. You are not broken.
You are a woman whose nervous system has been running on depleted resources, in a body that is changing in ways nobody ever properly explained to you. There is a physiological reason you feel the way you feel.
And when you address the underlying chemistry — rather than just pushing through, or writing it off as ‘just stress’, or numbing it with wine and chocolate at night — things genuinely change.
I’ve spent nearly 30 years helping women get to the bottom of exactly this. Not just managing symptoms. Instead, finding out why they’re there in the first place.
If this resonates and you’re ready to understand what’s actually driving your symptoms, I’d love to help you connect the dots.
Warmly,
Teressa,
Naturopath | Clinical Nutritionist | Biochemist
