I have noticed that the senses detach when I'm sleeping with hands on my chest too. In our community, it's believed that demons possess you if you sleep with hands on chest. Probably its because of this kind of feeling. Weird, indeed.
For me it's vision and hearing that seems to go; I'm aware that I'm still awake, but my mind has drifted off elsewhere and isn't processing any visual / auditory things anymore. Mostly if I'm dozing off in front of the TV.
That's super interesting! I've been doing some meditations lately while lying in bed, and I have my hands on my chest, and it is only during these times, when I've fallen asleep while meditating, that I have noticed myself snoring. I'm going to pay more attention to that now.