A few posts here and here.

It seems possible the vagus nerve is being stimulated by the work we do, and perhaps this is a reason why breastfed babies are more social than formula fed ones (eg: due to the increased oxytocin release through stimulating their palate during the feeding, then consequently adopting tongue on roof of mouth posture, correct swallow pattern, etc).

There are said to be some techniques to stimulate the nerve on your own, to help with various conditions, though this doctor who claims to be a world leader in this area says you need to stimulate it electrically (eg: implant, tVNS) to have any effect when damage to the parasympathetic is present. So either the implant or his new app for phones with the use of a certain device (though he'll currently only set you up if you have a face-to-face appointment with him). I keep reading on my forums about this subject that the devices you can buy to electrically stimulate the vagus nerve don't work well...

Something I've started doing which may help along these lines is gargling with a Mew cheesy smile. My eyes will tear up some which is said to be the intensity you need to do. But my thinking is it will take more than just Mewing and related techniques to get the autonomic nervous system working optimally again in adulthood.

Mdma 

No but seriously this sounds interesting. I know drugs can help but interesting how to without drugs

I have heard about Ayahuasca purging all of your trapped emotions somehow i want to try it but it seems scary

Posted by: Apollo

People like Plato and Dean Howell claim that cranial adjustments can only occur when the body is in a parasympathetic state. The preparatory work during NCR sessions, before the endonasial balloon inflation, is intended to get the body into this relaxed condition so that it doesn't resist the realignment of the sphenoid. I've seen quotes from Howell that are critical of palate expanders because they put the body under stress for too long. This is also Plato's rationale for short facepulling sessions to avoid kicking the body into a sympathetic mode. Obviously I am skeptical of this philosophy since I am using a palate expander for as many hours as possible every day, and I was trying to maximize my extra oral traction hours until I decided too much of that tension was loaded onto my teeth with my current setup. That being said, in my experience, it does feel easier to get my expander to fit comfortably when I am in a relaxed, parasympathetic mindset. One example is pushing the expander against my palate with my tongue during the deep nasal breathing exercises I am doing with the Frolov device. When I started thinking about my breathing exercises in the context of parasympathetic tone and vagal stimulation, I began to explore other strategies to stimulate the vagus nerve. I'm intrigued by ideas like om chanting and cold exposure, but I'm confused by one strategy. I've seen several sources suggest that fasting stimulates the vagus, but this seems to contradict the "rest and digest" mode, and fasting is supposed to raise cortisol levels and induce stress. I am not strict about intermittent fasting, but I often only eat during about 8 hours of the day with two meals. I could further restrict my hours, if fasting for 18+ hours of the day would be helpful, or maybe I should spread out my eating to avoid the stress of fasting.

ive heard that fasting for 24 hours can increase testosterone by insane amounts. yeah i do intermittent fasts every day too not sure but  i theorize having cfd doesnt allow us to breath how we should and maybe it stresses our system which doesnt allow us to be in these parasympathetic states. because if grown correctly i feel a lot of people wouldn't have to work on the vagus nerve. I think being relaxed could help growth or the nerve work well. who knows how important it actually is tho