No one really understand how psychedelics even work so you're not going to get a very accurate answer. However, psychedelics can and very often do enhance whatever you're feeling to an absurd degree so even if you're not fully aware that you might be more jittery than usual the shrooms can bring this out to where it is blatantly obvious, some days you're extremely calm both consciously and unconsciously so you trips are very deep and relaxed. I find if i'm in a cold environment, even if i'm not feeling very cold but if the temperature is just a little lower than normal I move a lot more and im more jittery, if the weather is warmer than usual im a lot more calm and free feeling, I like to lay down or just move leisurely. All these factors can play in to the sensations you're feeling on mushrooms