We’ve all heard it before that loud pop during a neck adjustment. For some, it’s satisfying. For others, maybe a little unsettling. But what if that familiar cracking sound actually affected how your brain works?
A study published in the journal Life (MDPI) in early 2025 explored this very question. Researchers in South Korea set out to examine what happens in the brain and nervous system when you hear the audible sound produced during a specific type of spinal manipulation. And the results were more than just noise.
The Research Behind the Crack
The study was conducted by a team led by researchers from Daejeon University and the Korea Institute of Oriental Medicine. It focused on upper cervical spinal manipulation, which targets the top of the neck, where the spine meets the skull. This area plays a key role in supporting the head and influencing how your nervous system functions.
Eighteen healthy adult volunteers took part in the trial. All received an upper neck adjustment while hooked up to sensitive equipment that measured their brainwave activity (via EEG) and autonomic nervous system responses (like heart rate variability and skin conductance).
Here’s the twist: some participants heard a crack (the “audible group”), while others didn’t (the “non-audible group”). This allowed the researchers to isolate whether the sound of the adjustment made any measurable difference, not just the movement.
Key Findings: Your Brain Reacts to the Pop
The most striking discovery? Participants who heard the audible cracking sound showed increased alpha brainwave activity immediately afterward, especially in the back part of the brain (the occipital and parietal lobes).
Alpha waves are associated with relaxation and calm focus, the kind of mental state you might have during meditation or light rest. So, the sound of that neck crack may actually prompt your brain to shift into a more relaxed rhythm.
There were other effects too:
- Lower skin conductance levels in the audible group, which usually indicates reduced stress or arousal.
- No significant changes in heart rate variability or brainwave activity were observed in those who didn’t hear a cracking sound.
In other words, it wasn’t just the movement of the adjustment, it was the audible feedback that appeared to make the biggest difference in how the body responded.
Why This Matters
The takeaway here isn’t just about chiropractic care or spinal manipulation, it’s about the connection between your senses and your nervous system.
Hearing the crack may serve as a kind of auditory confirmation for the brain, reinforcing a sense of release or relief. The results suggest this sound might help shift the brain into a more relaxed state, even if only temporarily.
This could also explain why people often report feeling calmer or lighter after hearing a satisfying “pop” during an adjustment, stretch, or even while cracking their knuckles.
However, the researchers are careful not to overstate the implications. The study involved only healthy young adults and a single session of manipulation. Longer-term effects or impacts on people with chronic pain or neurological conditions were not explored.
What’s Next?
While the study opens the door to exciting questions, it also highlights the need for further research. Scientists could explore:
- Whether repeated sessions with audible manipulation have lasting cognitive or emotional effects
- How people with anxiety, insomnia, or chronic stress might respond to these changes in brainwave activity
- Whether the brain’s reaction is driven more by the expectation of the sound or the actual mechanical release
For now, it’s a fascinating peek into how something as simple as a sound – especially one we usually don’t think much about, can ripple through the nervous system in surprising ways.
