I don't really consider this a "drug" as your body isn't producing any hormones or chemicals to induce this feeling.
I mean, jogging can be addicting, but exercise produces adrenaline and endorphines so that's understandable. This is just putting your brain at a certain frequency, making it easier to meditate, relax, etc. which may or may NOT be a good thing! I'm not saying everyone should be doing this, just putting it out there for debate.
I'm new to this, so can't really weigh in at this point other than to discuss my experiences.