There are two answers to this, and pretending they are the same answer does nobody any favours. One comes from a tradition roughly two thousand years old. The other comes from neuroscience departments over the last fifty years.
Both are worth knowing, and the gap between them is worth being honest about.
The traditional explanation
The classical framework describes channels — meridians — through which qi circulates, with points along them where that circulation can be influenced. Illness is understood as disruption to the flow, and needling as a way to restore it.
It is worth being straightforward: meridians are not anatomical structures. You cannot dissect one out. What they are is an organising system, refined over a very long period of careful clinical observation, that tells a practitioner where to needle for a given presentation.
That system still works as a clinical map. It is simply not a claim about anatomy, and the practitioners we would trust do not present it as one.
What the research has found
The physiological picture is genuinely well studied, and it is more interesting than the sceptical version suggests.
| Step | What happens | Evidence |
|---|---|---|
| 1. Insertion | The needle activates small sensory fibres in skin and muscle | Well established |
| 2. Local response | Adenosine is released at the needle site, a non-opioid painkiller | Demonstrated experimentally |
| 3. Spinal cord | The signal reaches the dorsal horn and modulates incoming pain signals | Well described |
| 4. Brain | Endorphins and related opioid peptides are released | Blocking opioid receptors reduces the effect |
| 5. Descending control | Serotonin pathways from the brainstem dampen pain signalling | Supported |
| 6. Wider effects | Changes in autonomic and immune activity | Active area, less settled |
If you want to read about how pain signalling itself works, rather than a practice’s summary of it, the NIH neurological institute’s overview of pain describes the pathways this all acts on.
Two frameworks, side by side
It helps to see where the two accounts agree, where they diverge, and where neither has an answer.
| Question | Traditional account | Physiological account |
|---|---|---|
| Why this point? | It lies on the relevant channel | It has a particular density of nerve endings and tissue characteristics |
| What does the needle do? | Regulates the flow of qi | Activates sensory fibres and triggers neurochemical release |
| Why the heavy feeling? | Arrival of qi at the point | Recruitment of deeper sensory fibres |
| Why retain the needles? | Time for the effect to take hold | Sustained afferent signalling |
| Why does it vary by person? | Different underlying patterns | Individual differences in pain processing |
The honest gaps
Three things are not settled, and any page that skips them is selling rather than explaining.
- There is no unified theory. Different models explain different clinical applications. Nobody has one account covering pain, nausea and allergic rhinitis at once.
- Sham needling often works. Sometimes nearly as well. That suggests a meaningful part of the effect is not specific to where the needle goes.
- The evidence varies enormously by condition. Strong for migraine prevention, weak for menopausal hot flashes. It is not one treatment with one success rate.
What “energy” does and does not mean here
Qi is usually translated as energy, and that translation causes more confusion than it resolves. It carries a New Age connotation in English that the original term does not have.
A closer reading is something like functional capacity — the body doing what it should, in the right place, at the right rate. Describing digestion as weak in that framework is a statement about function rather than about an invisible force.
Nothing about acupuncture requires believing in a field physics has not found. It requires a practitioner who knows the map, and a body that responds to being needled.
Why the gaps matter less than they sound
Not knowing precisely how something works is a normal state of affairs in medicine. Aspirin was in use for decades before its mechanism was understood, and general anaesthesia is still not fully explained.
The clinically useful question is not “how does it work” but “does it help with this, in people like me”. That question gets answered separately for every condition, which is why we have written about them separately — migraine, low back pain, knee osteoarthritis, seasonal allergies, jaw pain and carpal tunnel syndrome each have their own evidence picture, and they are not the same picture.
What this means in the treatment room
A practitioner trained in the traditional system uses it to decide where to needle, while understanding the physiological account of what the needle then does. The two are not in competition in practice, whatever they look like on paper.
It also explains why the intake conversation is so long. The traditional framework is highly individualised: two people with the same diagnosis may be treated quite differently based on sleep, digestion, temperature and pulse.
Booking a session in Beverly
Acupuncture is $75 a session, published with everything else on our rates page. If the practical questions are what you are really after, what a first session actually feels like covers those.
Read more about acupuncture at our Cabot Street practice, how to choose a licensed practitioner, or get in touch to book an appointment.
Frequently asked questions
Do meridians physically exist?
Not as anatomical structures that can be dissected out, no. Meridians are the organising framework of a traditional system, and they remain clinically useful for deciding where to needle. That is a different claim from saying they are vessels you could find under a microscope.
What does modern research say happens?
Needling activates sensory nerve fibres in skin and muscle. That signal reaches the spinal cord and brain and triggers the release of the body’s own opioid-like chemicals, including endorphins. Non-opioid mechanisms are involved too, including adenosine released locally at the needle site.
How do we know endorphins are involved?
Because blocking them blocks the effect. Naloxone, which occupies opioid receptors, reduces acupuncture analgesia. That is reasonably strong evidence that the opioid system is part of the pathway.
If sham acupuncture also works, does point location matter?
This is the genuinely open question. Sham needling often produces a real effect, which suggests some of the benefit is not point-specific. For some conditions acupuncture still beats sham; for others it does not. Honest practitioners hold both facts at once.
Does it matter that the mechanism is not settled?
Less than people assume. Plenty of accepted treatments worked before anyone could explain them. What matters clinically is whether it helps for your condition, which is a question the trials answer separately for each one.
This article is general information, not medical advice. Acupuncture is intended to work alongside the care of your doctor, not to replace it. Please speak to a clinician about any new, severe or changing symptom.