For the sake of usability I am going to attempt at a simpler explanation of how communication can cause mutual regulation between two people – Interregulation or co- regulation.
Interregulation is when two peoples’ emotional connection to each other causes an activation of the parasympathetic nervous system thereby making both parties feel relieved… connection is calming… connection comes from two people remaining emotionally open and authentic while receiving each other with empathy and compassion.
Lets start with my favorite and very common example:
for the sake of readability I am going to use pronouns of a heterosexual couple, but this would be the same for any two people (they don’t even need to be in a relationship)
So a man comes home from a long day at work and is visibly distraught… his hair has  felt the wrath of frustrated combing fingers and he has gritted the enamel off his teeth.
“My boss is such an ass… I come in to work today and he asks to see my finished report… so I tactfully remind him that my deadline isn’t for another week… he then humiliates me in front of the whole office saying that the deadline was changed last week in a meeting that I wasn’t at… he grabbed my arm and escorted me to the white board in the conference room, which sure enough read that the deadline was today.”
The husbands eyes carry a mix between terror and ferociousness… he is hot to the point of perspiration and he can hear his pulse banging like a wet drum. He is flooded and needs help from his partner to find regulation.
The wife too is now extremely stressed for three reasons: One, through the process of attuning to her husband empathetically she has picked up much of his emotional energy. The situation is so tense that she is not afforded the time to reflect upon the truth that this is not actually her energy… she then unconsciously has embodied the emotional disposition of her husband. Two, automatic thoughts about what she ‘should do’ are racing through her head and she unintentionally starts to shame herself as she has already concluded that she can not help her husband and is worried that she is actually going to make things worse. Third, She desperately wants to escape this emotion that is so violently attacking her central nervous system… she wants to help her husband, but her body wants to help itself by leaving the stressor (which is her husband’s emotion).
She is disregualted and he is disregulated… we now have two people with an over-activated central nervous system.
she turns to him and says, “we’ll I guess you will just have to make a point of checking to see if there are any important notes on the whiteboard.”
The suggestion sends the husband over the edge and he explodes into a disconnected rant about the 21st century and email communication.
It is so easy to pick sides in these interactions, but no one was actually at fault and they both had a common goal.
What was needed for Interregulation? the wife needed to feel competent in soothing her over-activated husband and the husband needed to feel emotionally understood and validated.
The healing variable would have be a feeling of connected-ness which would have facilitated regulation by calming their limbic systems. (I know this seems stupidly simple, but it does work – fear is disregulating… fear is an automatic emotional reaction to feeling separate… and connected-ness is regulating… connected-ness can activate our parasympathetic nervous system, which is the rest and digest state of being.)
Sooo…
the very next time this happens the wife states. “your fucking kidding me… hasn’t that asshole heard of email? I am so sorry honey that must have been impossibly aggrivating… and, ” she offers a somber facial expression,” so humiliating in such an unfair way…”
He softens feeling both seen and validated and allows himself to regulate in her embrace. She never lost connection to her partner and therefor was able to both self-regulate and co-regulate into the connectedness. Further, she feels supportive and she feels his openness… this further regulates her and he then can absorb this through their embrace.