The third sense is known as proprioception. This, put simply, is the brain's knowledge of the relative positions of the body's parts. The loss of this ability is known by several names. Proprioception Deficit Disorder, Sacks' Syndrome, and Descartes' Disease are all titles for the same illness, which is a complete and total failure of the body's knowledge of itself. Since it is a rare disorder, it is difficult to say what the premonitory symptoms are. However, there have been reports that the first symptoms are extremely vivid dreams of lost motor function or physical control. These are followed by an increasing lack of coordination, culminating in full-blown proprioceptive failure. ...

The third sense is known as proprioception. This, put simply, is the brain's knowledge of the relative positions of the body's parts. The loss of this ability is known by several names. Proprioception Deficit Disorder, Sacks' Syndrome, and Descartes' Disease are all titles for the same illness, which is a complete and total failure of the body's knowledge of itself. Since it is a rare disorder, it is difficult to say what the premonitory symptoms are. However, there have been reports that the first symptoms are extremely vivid dreams of lost motor function or physical control. These are followed by an increasing lack of coordination, culminating in full-blown proprioceptive failure. At this point, the human mind is completely unaware of its own body. Sufferers report a "disembodied" feeling, as if the mind and body have completely separated.

Whoa. This is fascinating. I hope Discovery Health does a show about this.