Pillow Talk

You climb into bed at the end of a long day. Your head hits the pillow, you close your eyes, and you:

• Fall immediately asleep?
• Lie there tossing and turning?
• Jump awake as a thought or image flashes in your mind?

If it's any comfort to you, scientists still can't say exactly what happens when we begin to nod off. But once they figure it out, they may be able to offer concrete help to the 30 to 35 percent of people who suffer from insomnia.

Researchers representing some 26 different sleep labs will pm-sent their pat theories on so-called sleep transition at a conference this summer. John Harsh, Ph.D., of the University of Southern Mississippi, for one, is focusing on sleep apnea. While it's long been known that the lack of oxygen the condition produces can sometimes wake us up, more often it causes a transition from a deeper to a lighter stage of sleep, often hundreds of times a night. That, Harsh believes, may provide further clues as to what goes on when we try to sleep.

Once thought of as a "switch being thrown" from wakefulness to sleep, sleep onset is now seen as is now seen as a phase in which we continue processing a great deal of information--as we do during sleep itself, though to a lesser degree. We are much more active than previously recognized--for example, we respond to names (especially our own), and to other info such as room termperature.

There is even what Harsh calls "situation-specific receptivity." A new mother, for example, might be especially sensitive to her baby's cry while father might awaken in response to the sounds of a prowler.

Though interest in sleep has boomed recently, the subject of sleep transition is just beginning to see the light of day.