We are constantly bathed in a multitude of energy fields...with dedicated practice, you can become more aware of such subtleties. I myself am not super sensitive...but like a very wise taiji guy I know once said, 'you're not any more or less sensitive than I...it is simply a matter of being aware.' Which can be a confusing concept when one isnt aware of what one isnt aware of
As far as reiki goes, a close buddhist friend of mine completed all 3 levels of reiki, just to understand what it was...and once he discovered the root of it, he tore his certifications up. I would not allow anyone to do reiki on me, that's all I'll say on the matter.
For a more readily comprehensible concept, one thing I discovered how to do is more efficiently draw in heat through the laogongs, that's a nice unsubtle way to expose oneself to an energy field. You just need a fire or other good heat source like the heat vent on your car perhaps. Hold the hands up and inhale/sip the heat through the laogong cavities and the heat travels up the channel, virtually disappearing at the sea (
he point) and then reappears, joined from both sides at the shen dao t5 point (for me when that happens the is a shuddering equalization of heat and after a few reps it makes one nice and toasty.) Kinda like the (tail end) reverse of how John Chang employs yin yang gong
To begin becoming aware of more subtle things, sit in stillness. Quiet the breath until you are only breathing with the dan tien, no turbulence. Practice sincerely every day, and things will manifest of their own accord