Dream On!


by Guy McKhann, M.D.

April 12, 2010

“To sleep, perchance to dream-
Ay, there’s the rub”
—Hamlet

My late colleague, William Safire, was well known as a word maven. In recent years, as part of his role as chairman of the Dana Foundation, he applied his talents to the brain, popularizing such titles as “neuroethics,” and “neuroeducation.” I will respond to his influence by perhaps introducing you to a similar term: “neuroblogger.”

This species of communicator focuses on brain functions and disorders, with varying degrees of expertise. However, chief among them is an established neuroscientist and author, Jonah Lehrer, who recently published a marvelous book, “Proust Was a Neuroscientist.” His blog is called “The Frontal Cortex.”

In this issue we highlight one of his recent contributions: “Why We Need to Dream.” Dreaming as a phenomenon has intrigued authors, musicians, psychologists, and brain scientists for centuries. (Witness the quote, above, from Shakespeare’s Hamlet, written more than 400 years ago, in 1603.)

There are physiologic aspects of dreaming that are now recognized and studied. We do not dream throughout our sleeping period, but at intervals during sleep, known as REM sleep (REM stands for “rapid eye movement). Most dreaming, but not all, occurs during these REM periods. Thus when someone is dreaming, one can see the eyes moving beneath the closed eyelids. In his article, Dr. Lehrer describes observing this in his wife. If you wake up the person at those times, they can describe their dreams, most of which they would not normally remember on awakening.

During these phases of sleep, the brain shuts off motor movements. So, if you are dreaming of running, or playing basketball against Duke, you do not make the associated movements. This lack of movement not only keeps you from injuring yourself, but also protects your bed partner from getting whacked. Occasionally I have seen a patient who has lost this inhibition of movement during dreaming, with resulting interesting stories—often by the bed-partner. Fortunately this inhibition can be restored with medications.

But why do we dream? Shakespeare would probably say “Ay-that’s the question!” There are many speculations, but no definitive answers. These ideas fall into several categories that are not mutually exclusive:

Consolidation: That is, we take the randomly collected information we have acquired while awake and correlate it with what we know already, with the result being a more coherent body of knowledge.

Pruning: Francis Crick, of Double Helix fame, later turned his attention to the brain. He hypothesized that “We dream to forget.” In other words, we filter out much of the useless, or less important information, we have acquired during the day and consolidate the important data.

Creating: Lehrer alludes to this function in his blog. Analysis of a problem, while dreaming, leads to a solution There have been notable discoveries in which the scientist is said to have woken up, grabbed a pencil by the bedside and scribbled down an idea or possible experiment. In fact, this happened to me recently. I had a vivid dream, woke up and thought, “Wow, that is a slick idea.” Then I realized I hadn’t even been working on the problem I just solved. I was going to call a colleague, but since it was about 4 a.m., I restrained myself. By morning, I realized my dream-inspired idea wasn’t all that original. Oh well, better luck next dream!