I find my self in the state of heightened awareness that you describe off & on and after every yoga class I take. Feels like I'm in a meditative state but with full awareness and control.
If you haven't tried yoga, I would suggest it. Since I've started attending a class regularly (3 months ago), I find myself in that state of high awareness randomly throughout the week even if I have not attended class that day.
It is one of the most amazing experiences I have ever felt.