I am bolstering my practice with the Wim Hof Fundamentals course, and am currently in Week 8 which has an extra focus on meditation over and above the regular practice. The aim this week is to oxyegenate the body and then focus the blood towards the pineal gland and brain stem for non-conceptual meditation and, in Wim's words 'to decalcify the pineal gland' whatever that means.

So today I did this and had a new experience - aside from the usual piti and nimitta.  As I meditated according to the instructions, I had some energetic body movements, then a feeling of lightness grew, and then spaciousness and a kind of dizziness (but without any diorientation).  Then I found myself in a stable, non-conceptual, open, slightly stoned state.  It is quite 'up' with no hint of dullness, and a very slight buzziness and euphoria.  It is really a pretty nice state.  But seems more like a drug than anything related to jhanas or liberation.

Anybody know what this is?  I guess it is the release of some chemical in the brain.

Do you mean "up" in an alert way, or in a directional way, like straight up through the crown of the head?

Up in an alert way.  Kind of like mild pscyhological arousal but without an object for that arousal/activation.