Mind and brain: How do unconscious people know when to wake up?

Spiritual Brain friend David Rice writes to say,

Hey Denyse - I work at the library's circulation desk at the University of MS and noticed a book just lying around entitled "Understanding Sleep and Dreaming" by William Moorcroft. I started leafing through it and noticed this interesting blurb. On page 118 (Box 15 inset) he writes that there was a study done which concluded that when people EXPECT to be awakened at a certain time that their bodies will begin to produce adrenal corticotropic hormone (which tells the adrenal glands to release cortisol) at they time necessary to awaken thus facilitating that awakening process. Others, who were told that they could sleep in, did not produce this hormone if they were awoken BEFORE the time they actually EXPECTED to awaken. Thus the mind appears to have a causal role, non-materialistic, on the bodies preparations for arising from sleep depending on what they mind expects will happen. Provocative no?

Yes indeed. I asked lead author Mario Beauregard about it and he said, "This finding effectively supports the view proposed in our book regarding the causal influence of mind processes on brain/body functioning."

I suspect there are many similar examples out there, but if we are not looking for them we won't notice them.