Sleep Pattern Differences between Minimally Conscious and Vegetative States →

In conclusion, we observed behavioural, but no electrophysiological, sleep wake patterns in patients in a vegetative state, while there were near-to-normal patterns of sleep in patients in a minimally conscious state.

This helps us understand what it means to be conscious.  This particular quirk is scary to me because we heal during sleep.  Growth hormones are released during deep sleep periods - without which we cannot regenerate (these periods also tend to decrease as you get older).