On days when I'm spending several hours studying for biology, after a while, I can feel a bit weird. I feel a loss of self-feeling and self-perception, as if everything is going on around me entirely on its own and I am simply drifting along, like a cloud in the sky, a feather in the wind, or a piece of driftwood on a river. Psychologists call this "flow". Not seeing everything as I or mine, I have somewhat of a clearer perspective on things... Not being anxious about past or future sufferings, or necessary actions in the present to address both. So, I see it as a feeling of kensho (since after a few hours or a night's rest, it's gone).
And yet, this is not traditional "meditation, is it? So, why should it make me feel this way?
Can concentration merely by itself yield positive results, without using specific objects or contexts? (Sitting down for 30 minutes, focusing on one of the 40 objects of meditation, in a manner prescribed by a teacher, etc..)