That's soOo wonderful, isn't it? I really do feel there's something in our system/Soul/Brain/Consciousness that when we sleep, part of our brain turns off and the other has more, "wiggle-room?"
The dream you described...it's like a part of us travels and we really are there.
Even if it were to be a scientific thing and the body produces energy or electric currents of some type and we're mostly water, when dreams like that happen, it really feels like you are connecting with some part of the other person's energy.
I've had dreams, where the person is still living and haven't spoken to them in 8 mnths or so. I'll see them packing or something and a day or two later, the person calls or I'll call them and this part is funny -
If they're doing something they swore they'd never do, I'll pick up the phone and the first thing out of my mouth is, "WHAT are you doing...!?!" Like a mother to a kid, lol.