From the May 26 BRAIN/MIND BULLETIN:

According to Ernest Rossi, a Los Angeles psychologist, most of us are unaware that periodically throughout the day, we enter natural trances. The apparent continuity that exists in everyday awareness, Rossi explains, is a "precarious illusion" based on conversation, task orientation and the like.

But still, the mind wanders, and memories flow easily. Some people catch fleeting glimpses of "the big picture," while others become so entranced that they neither see nor hear. Others may feel uncomfortable and try to suppress what Rossi calls "personal truths that come unbidden during these naturally unguarded periods."

The Basic Rest and Activity Cycle, which is at the root of these trance states, is an ultradian rhythm -- a shift that occurs about every 90 minutes. Researchers have reported a left-to-right hemisphere shift as breathing changes from the right nasal passage to the left. The crossover period lasts roughly 10 minutes. Among the visual cues that accompany the shifts are relaxation, reduced blinking, pupil dilation, reddening of the eyes, respiratory slowdown, and sweating.

Rossi reports on everyday trances in a new volume on current research and theory entitled HANDBOOK OF STATES OF CONSCIOUSNESS, edited by Benjamin Wolman and Montague Ullman (Van Nostrand).