There are MAOIs in tobacco smoke. I'm not sure that's what makes me feel calm though.
It also made me a little bit manic, and weaning off it sucked, but it worked well in general.
My mom recently switched to e-cigarettes, and she said that she still occasionally gets the urge to smoke a real cigarette. But she said the urge is a lot weaker than when she used to go prolonged periods without smoking cigarettes, such as after a long plane ride.
For me the addiction was partly psychological around the form factor. Using "light sabre" style vapes didn't work. However I was able to wean myself off smokes using realistic e-cigs (which I also eventually quit).
I've been smoking for a little over 20 years (since a teenager). Good luck.
If you try it. make sure you get fresh stuff before you pass judgment, because it ferments inside the package if left out for too long.
https://www.nytimes.com/2014/11/30/business/studying-snus-a-...