Quote Originally Posted by grasshoppa View Post
From what I've heard they can basically increase serotonin levels at will (as well as other chemicals), creating highs while meditating.
On a tangent, this is something I've managed to pull off numerous times, but I've drastically lowered its frequency thanks to the potential risk for irreversible psychological damage if abused. I'm sure that each individual who starts to alter their biological functions through conscious intent will experience some sort of change in their health, positive or negative, as they develop more and more control over these sort of things.

Because of my personal experience, I believe it's possible. However, the extent to which it can go is unknown to me, and might be unknown to even the scientific community unless we hook up a monk to an array of biological sensors and let them do their thing.