Excerpt from The Mind at Night by Andrea Rock, plus links to reviews, author biography & more

Rechtschaffen came up with a novel way to test whether signals transmitted from the retina (the gateway for visual information from the outside world to the brain in waking) played a role in creating dream imagery. Amazingly he succeeded in getting test subjects to go to sleep with their eyelids taped halfway open. Once the sleeper entered REM, Rechtschaffen would sneak into the bedroom with a small light to illuminate objects such as a comb, book, or coffeepot that he would hold up in front of the sleeper’s taped-open eyes. Then he would exit, and his research colleague David Foulkes would awaken the subjects via intercom and ask what they had been dreaming about. None of the dreamer’s reports included images of the objects that had been dangled in front of their eyes. Clearly dream imagery was generated internally, though it wasn’t yet clear how.

Additional experiments indicated that except for some decrease in the clarity of background detail and intensity of color, the quality of visual images we see in our dreams is nearly on a par with what we see when we’re awake. Most dreams are also clearly experienced in color, though for some unknown reason, between 20 and 30 percent play out in black and white. While reports on dreams all the way back to Aristotle included references to color, from the 1930s to 1960, the prevailing opinion among research psychologists as well as among the general public was that we dream in black and white. Not coincidentally, this period was also when photographs and film images were primarily black-and-white. Though color photography was invented in the 1860s, it did not become readily available for public consumption until the 1940s. Similarly, Technicolor made a big splash beginning in the late 1930s with a few movies such as The Wizard of Oz, but full-color films didn’t become common until the 1950s.

During this period, when psychologists asked their subjects if they dreamed in color, the majority said no: a 1942 survey of college students found only 10 percent claimed to frequently dream in color, and only 9 percent reported dreaming in color in a 1958 study at Washington University in St. Louis. But when sleepers in a 1962 study were actually awakened during REM sleep and asked directly about the appearance of color while their dreams were in progress, 83 percent reported color in their dreams. "It is surely not chance that this flourishing of black and white media coincided with the flourishing of the opinion that dreams are a black and white phenomenon," says Eric Schwitzgebel, a University of California at Berkeley professor who studied this curious trend and concluded that it wasn’t the content of dreams that had changed during that period but public perception--or more accurately misperception--of dream imagery. In short, it was another example of the pervasive power of suggestion that can make eyewitness accounts in criminal investigations so unreliable.

While many investigators were focusing on unraveling the secrets of dreaming per se, others examined the underlying state in which it occurs, trying to understand why we need sleep at all. In addition to working on developing standards used today for classifying different stages of sleep, Allan Rechtschaffen and his students investigated what happened when animals were deprived of sleep. They conducted sleep deprivation experiments in rats and found that those deprived of all sleep died after two to three weeks. The sleep-deprived rats became extremely debilitated and had difficulty regulating body temperature, but the cause of death could not be isolated.

Less extreme studies in humans showed that when deprived of REM sleep, subjects automatically compensated by entering REM sooner and staying in it longer the next time they went to sleep. A similar rebound effect was seen for the deeper slow-wave sleep, so obviously both types are essential. In fact, nature itself provides evidence suggesting that total sleep deprivation can eventually cause death in humans. A rare genetic disease called fatal familial insomnia (FFI) was first identified in 1986 as the cause of death of thirty members of an aristocratic Italian family. Since then, the disorder has been identified in thirty other families around the world. Those suffering from the genetic disorder typically lose their ability to sleep when they reach middle age, though some have been struck in their teens. After weeks without sleep, FFI victims’ pulse and blood pressure rise and they sweat heavily. They then have difficulty maintaining their balance, walking, and/or speaking and in the final phase--usually after several months without sleep--they fall into a state akin to a coma and die. The disease severely damages a portion of the brain called the thalamus (the sensory gateway to the cortex). Further research is needed to determine whether the insomnia or the thalamic damage directly causes death.

From The Mind at Night, chapter 1, pages 1-16. Copyright 2004 by Andrea Rock. All rights reserved. No part of this book may be reproduced in any manner whatsoever, except for brief quotations embodied in critical articles with reviews, without written permission from the publisher, Basic Books.