Then you're doing something different (not claiming wrong if it works for you) than what meditation generally is supposed to achieve. There can be various reasons, but its definitely not the standard output nor in me nor any person I know is meditating.
I am guessing you are not suggesting that the goal with meditation is to achieve cold hands, so maybe you are assuming that my heart rate goes up or something similar. However, I can assure you that is not the case.
There are theories that Raynaud's syndrome (unreasonably cold hands and feet) can be triggered by stress and so one could hypothesize that the opposite holds true as well. That may be related, or it may not be. I am just pointing out that such a simplistic view of something so extremely complex like our bodies can be misleading.
I am not writing about cold hands, feet or Raynaud's syndrome or any other health issues, don't know where you did take it from. I am talking about slowing heart rate, and subsequently the body will slightly cool down, depending on how much you slow down the heart rate. Of course extremities is where cooling down is felt first, but this is normal for any healthy human.
This is a normal reaction of any healthy body (lower heart rate -> lower temperature), ask any doctor or consult any relevant medical book. This experience also comes from my fiancee who is a doctor, with same reasoning. Something they use sometimes at their work (or reverse effect).
You might be doing something during your meditation that counters this natural effect (physically or mentally), I don't know and frankly it's not much relevant to the discussion. Or do you have any scientific resource that proves the opposite effect is true?
