What makes a sick person's eyes roll back in his head?

The eyes of a sick person do not always roll back into the head, but for those that do, there may be several answers. The most likely answer and cause relates to sleep. When we sleep, we have what is known as Bell's phenomenon. First described by Charles Bell in 1823, our eyes deviate upward and outward with forced lid closure, and in many with more passive lid closure with sleep. The rolling of the eyes with some serious illnesses is probably mediated by the same mechanism as the Bell's phenomenon and resembles what happens in most of us while we sleep. As we close our lids, the eyes go up and out, at least to some extent. While we don't know exactly what that mechanism is, there may be involvement of two cranial nerves including the one that moves our facial muscles known as the facial nerve (number seven for those who are interested) and one of the nerves that helps move our eye though eye muscles (the third nerve for those who are interested). So the eyes may be rolling up in the head with a near-sleep state, although there could be other reasons as well.