a] Your heart rates slows down very much during meditation ---so that means your heart is pump blood very slowly, as if you were asleep ---so you have to cover yourself with a blanket during meditation in advance of you loosing the warmth of your body's high degree of inaction. b] Apparently you are quite capable of meditating with full attention ---the research of Tibetan monks minds during meditation was the opposite of quite slowed-down mental activity, rather the test showed the the mind attained a state of High-alertness. You may be encountering two wholley different reactions that only seem to be connected one to the other. The anxious urgency of attaining a state of tranquility has left you hyper awareness that you may mis-construe as just more mind chatter. The same goes with the low body temperature due to low heart rate. Remember, "Heat" travels toward the "cold" so as to dissipate into the cold. c] Active-moving meditative routines may focus your quick intellect. The samurai sought "Mushin" (no-mind) via saizen meditation ---so as to be clam-minded during fighting. The state of Mushin combined with the expert samurai's personal sense of self-preservation was a Zen Master's tight-rope moment in the spot light. Such samurai probably worked up a sweat during their work outs between daily seizen exercises. d] Classical Silent Meditation is very specific and simplistic ---such meditation is not the same thing as Mental Contemplation. Mental Contemplation is an invocation of revelry via the action of mental defragmentation. During Defragmentation of the mental CPU it is advised to wait for the process the end before utilising other programs.