Well, I have been running an experiment.  I always run them on myself.  I did yoga daily for 25 years, (except when I was having kids - my body did not cooperate). And in the first 2000 decade I started meditating everyday.  Although I didnt live in a cave and devote all of my time to sacred scripture reading, practicing yamas and niyamas, but rather lived a life with kids, relationships and much material success, I found my consciousness quite expansive, my awareness very present, mindfulness always there.  The sense of ego was diminishing and I experienced life as if the "I" was just part of the "one".  As I surrendered more and more to what was, my ego (sense of individual self) had less and less to do with what manifested in my life, and yet life manifested quite a lot.

At some point a decision was made to not continue so strong a practice, perhaps mind won a small battle, and I lessened the meditation practice and lessened the yoga practice.  I even stopped the practice altogether for many months.  Although there was still the sense of less I and more one, the change in awareness and expansive consciousness had been quite extreme.  In other words,
No Meditation = No Awareness.  Over time the state of presence and mindfulness decreased more and more.

All of that led me to consider that this really is a function of neurons in the brain, .and not some potential spiritually induced enlightenment.  The more I practice(meditation/yoga), the more the neurons in my brain become wired in a spacious, unreactive, surrender leaning way.  The less I practice, the more stressed I react and less open and spacious I feel.

It take 7 years to replace all the neurons in our brains.  In this 2nd phase of the experiment I hope to locate the happy medium range of awareness and functioning on this plane(t).