In response, I look intensely and knowingly at Kyle, having been nodding my head throughout his description. I pause, and then say, “I know exactly what your dream is about, Kyle.” Amazed, he (and the rest of the lecture hall) awaits, my answer as though time has ground to a halt. After another long pause, I confidently enunciate the following: “Your dream, Kyle, is about time, and more specifically, about not having enough time to do the things you really want to do in life.” A wave of recognition, almost relief, washes over Kyle’s face, and the rest of the class appear equally convinced.
Then I come clean. “Kyle—I have a confession. No matter what dream anyone ever tells me, I always give them that very same generic response, and it always seems to fit.” Thankfully, Kyle is a good sport and takes this with no ill grace, laughing with the rest of the class. I apologize once again to him. The exercise, however, importantly reveals the dangers of generic interpretations that feel very personal and uniquely individual, yet scientifically hold no specificity whatsoever.
I want to be clear, as this all seems dismissive. I am in no way suggesting that reviewing your dreams yourself, or sharing them with someone else, is a waste of time. On the contrary, I think it is a very helpful thing to do, as dreams do have a function, as we will read about in the next chapter. Indeed, journaling your waking thoughts, feelings, and concerns has a proven mental health benefit, and the same appears true of your dreams. A meaningful, psychologically healthy life is an examined one, as Socrates so often declared. Nevertheless, the psychoanalytic method built on Freudian theory is nonscientific and holds no repeatable, reliable, or systematic power for decoding dreams. This, people must be made aware of.
In actual fact, Freud knew of this limitation. He had the prophetic sensibility to recognize that a day of scientific reckoning would come. The sentiment is neatly encapsulated in his own words when discussing the origin of dreams in The Interpretation of Dreams, where he states: “deeper research will one day trace the path further and discover an organic basis for the mental event.” He knew that an organic (brain) explanation would ultimately reveal the truth of dreams—a truth that his theory lacked.
Indeed, four years before he descended into a nonscientific, psychoanalytic theory of dreaming in 1895, Freud initially tried to construct a scientifically informed, neurobiological explanation of the mind in a work called the Project for a Scientific Psychology. In it are beautiful drawings of neural circuits with connecting synapses that Freud mapped out, trying to understand the workings of the mind while awake and asleep. Unfortunately, the field of neuroscience was still in its infancy at the time. Science was simply not up to the task of deconstructing dreams, and so unscientific postulates such as Freud’s were inevitable. We should not blame him for that, but we should also not accept an unscientific explanation of dreams because of that.
Brain scanning methods have offered the first inklings of just this organic truth about the source of dreams. Since autobiographical memory regions of the brain, including the hippocampus, are so active during REM sleep, we should expect dreaming to contain elements of the individual’s recent experience and perhaps give clues as to the meaning, if any, of dreams: something that Freud elegantly described as “day residue.” It was a clear-cut, testable prediction, which my longtime friend and colleague Robert Stickgold at Harvard University elegantly proved was, in fact, utterly untrue … with an important caveat.
Stickgold designed an experiment that would determine the extent to which dreams were a precise replay of our recent waking autobiographical experiences. For two weeks straight, he had twenty-nine healthy young adults keep a detailed log of daytime activities, the events they were engaged in (going to work, meeting specific friends, meals they ate, sports they played, etc.), and their current emotional concerns. In addition, he had them keep dream journals, asking them to write down any recalled dreams that they had when they woke up each morning. He then had external judges systematically compare the reports of the participants’ waking activities with their dream reports, focusing on the degree of similarity of well-defined features, such as locations, actions, objects, characters, themes, and emotions.
Of a total of 299 dream reports that Stickgold collected from these individuals across the fourteen days, a clear rerun of prior waking life events—day residue—was found in just 1 to 2 percent. Dreams are not, therefore, a wholesale replay of our waking lives. We do not simply rewind the video of the day’s recorded experience and relive it at night, projected on the big screen of our cortex. If there is such a thing as “day residue,” there are but a few drops of the stuff in our otherwise arid dreams.
But Stickgold did find a strong and predictive daytime signal in the static of nighttime dream reports: emotions. Between 35 and 55 percent of emotional themes and concerns that participants were having while they were awake during the day powerfully and unambiguously resurfaced in the dreams they were having at night. The commonalities were just as clear to the participants themselves, who gave similarly confident judgments when asked to compare their own dream reports with their waking reports.
If there is a red-thread narrative that runs from our waking lives into our dreaming lives, it is that of emotional concerns. Counter to Freudian assumptions, Stickgold had shown that there is no censor, no veil, no disguise. Dream sources are transparent—clear enough for anyone to identify and recognize without the need for an interpreter.
DO DREAMS HAVE A FUNCTION?
Through a combination of brain activity measures and rigorous experimental testing, we have finally begun to develop a scientific understanding of human dreams: their form, content, and the waking source(s). There is, however, something missing here. None of the studies that I have described so far proves that dreams have any function. REM sleep, from which principal dreams emerge, certainly has many functions, as we have discussed and will continue to discuss. But do dreams themselves, above and beyond REM sleep, actually do anything for us? As a matter of scientific fact, yes, they do.
Chapter 10
Dreaming as Overnight Therapy
It was long thought that dreams were simply epiphenomena of the stage of sleep (REM) from which they emerge. To illustrate the concept of epiphenomena, let’s consider the lightbulb.
The reason we construct the physical elements of a lightbulb—the glass sphere, the coiled wire element that sits inside, the screw-in electrical contact at the base—is to create light. That is the function of the lightbulb, and the reason we designed the apparatus to begin with. However, a lightbulb also produces heat. Heat is not the function of the lightbulb, nor is it the reason we originally fashioned it. Instead, heat is simply what happens when light is generated in this way. It is an unintended by-product of the operation, not the true function. Heat is an epiphenomenon in this case.
Similarly, evolution may have gone to great lengths to construct the neural circuits in the brain that produce REM sleep and the functions that REM sleep supports. However, when the (human) brain produces REM sleep in this specific way, it may also produce this thing we call dreaming. Dreams, like heat from a lightbulb, may serve no function. Dreams may simply be epiphenomena of no use or consequence. They are merely an unintended by-product of REM sleep.
Rather a depressing thought, isn’t it? I’m sure many of us feel that our dreams have meaning and some useful purpose.
To address this stalemate, exploring whether dreaming, beyond the stage of sleep it emerges from, has true purpose, scientists began by defining the functions of REM sleep. Once those functions were known, we could then examine whether the dreams that accompany REM sleep—and the very specific content of those dreams—were crucial determinants of those adaptive benefits. If what you dream about offers no predictive power in determining the benefits of that REM sleep, it would suggest that dreams are epiphenomenal, and REM sleep alone is sufficient. If, however, you need both REM sleep and to be dreaming about specific things to accomplish such functions, it would suggest that REM sleep alone, although neces
sary, is not sufficient. Rather, a unique combination of REM sleep plus dreaming, and dreaming of very particular experiences, is needed to transact these nighttime benefits. If this was proven, dreams could not be dismissed as an epiphenomenal by-product of REM sleep. Rather, science would have to recognize dreaming as an essential part of sleep and the adaptive advantages it supports, above and beyond REM sleep itself.
Using this framework, we have found two core benefits of REM sleep. Both functional benefits require not just that you have REM sleep, but that you dream, and dream about specific things. REM sleep is necessary, but REM sleep alone is not sufficient. Dreams are not the heat of the lightbulb—they are no by-product.
The first function involves nursing our emotional and mental health, and is the focus of this chapter. The second is problem solving and creativity, the power of which some individuals try to harness more fully by controlling their dreams, which we treat in the next chapter.
DREAMING—THE SOOTHING BALM
It is said that time heals all wounds. Several years ago I decided to scientifically test this age-old wisdom, as I wondered whether an amendment was in order. Perhaps it was not time that heals all wounds, but rather time spent in dream sleep. I had been developing a theory based on the combined patterns of brain activity and brain neurochemistry of REM sleep, and from this theory came a specific prediction: REM-sleep dreaming offers a form of overnight therapy. That is, REM-sleep dreaming takes the painful sting out of difficult, even traumatic, emotional episodes you have experienced during the day, offering emotional resolution when you awake the next morning.
At the heart of the theory was an astonishing change in the chemical cocktail of your brain that takes place during REM sleep. Concentrations of a key stress-related chemical called noradrenaline are completely shut off within your brain when you enter this dreaming sleep state. In fact, REM sleep is the only time during the twenty-four-hour period when your brain is completely devoid of this anxiety-triggering molecule. Noradrenaline, also known as norepinephrine, is the brain equivalent to a body chemical you already know and have felt the effects of: adrenaline (epinephrine).
Previous MRI studies established that key emotion- and memory-related structures of the brain are all reactivated during REM sleep, as we dream: the amygdala and emotion-related regions of the cortex, and the key mnemonic center, the hippocampus. Not only did this suggest the possibility that emotion-specific memory processing was possible, if not probable, during the dreaming state, but now we understood that this emotional memory reactivation was occurring in a brain free of a key stress chemical. I therefore wondered whether the brain during REM sleep was reprocessing upsetting memory experiences and themes in this neurochemically calm (low noradrenaline), “safe” dreaming brain environment. Is the REM-sleep dreaming state a perfectly designed nocturnal soothing balm—one that removes the emotional sharp edges of our daily lives? It seemed so from everything neurobiology and neurophysiology was telling us (me). If so, we should awake feeling better about distressing events of the day(s) prior.
This was the theory of overnight therapy. It postulated that the process of REM-sleep dreaming accomplishes two critical goals: (1) sleeping to remember the details of those valuable, salient experiences, integrating them with existing knowledge and putting them into autobiographical perspective, yet (2) sleeping to forget, or dissolve, the visceral, painful emotional charge that had previously been wrapped around those memories. If true, it would suggest that the dream state supports a form of introspective life review, to therapeutic ends.
Think back to your childhood and try to recall some of the strongest memories you have. What you will notice is that almost all of them will be memories of an emotional nature: perhaps a particularly frightening experience of being separated from your parents, or almost being hit by a car on the street. Also notice, however, that your recall of these detailed memories is no longer accompanied by the same degree of emotion that was present at the time of the experience. You have not forgotten the memory, but you have cast off the emotional charge, or at least a significant amount of it. You can accurately relive the memory, but you do not regurgitate the same visceral reaction that was present and imprinted at the time of the episode.fn1 The theory argued that we have REM-sleep dreaming to thank for this palliative dissolving of emotion from experience. Through its therapeutic work at night, REM sleep performed the elegant trick of divorcing the bitter emotional rind from the information-rich fruit. We can therefore learn and usefully recall salient life events without being crippled by the emotional baggage that those painful experiences originally carried.
Indeed, I argued that if REM sleep did not perform this operation, we’d all be left with a state of chronic anxiety in our autobiographical memory networks; every time we recalled something salient, not only would we recall the details of the memory, but we would relive the same stressful emotional charge all over again. Based on its unique brain activity and neurochemical composition, the dream stage of REM sleep helps us avoid this circumstance.
That was the theory, those were the predictions; next came the experimental test, the results of which would take a first step toward falsifying or supporting both.
We recruited a collection of healthy young adults and randomly assigned them to two groups. Each group viewed a set of emotional images while inside an MRI scanner as we measured their emotional brain reactivity. Then, twelve hours later, the participants were placed back inside the MRI scanner and we again presented those same emotional images, cuing their recollection while again measuring emotional brain reactivity. During these two exposure sessions, separated by twelve hours, participants also rated how emotional they felt in response to each image.
Importantly, however, half of the participants viewed the images in the morning and again in the evening, being awake between the two viewings. The other half of the participants viewed the images in the evening and again the next morning after a full night of sleep. In this way, we could measure what their brains were objectively telling us using the MRI scans, and in addition, what participants themselves were subjectively feeling about the relived experiences, having had a night of sleep in between, or not.
Those who slept in between the two sessions reported a significant decrease in how emotional they were feeling in response to seeing those images again. In addition, results of the MRI scans showed a large and significant reduction in reactivity in the amygdala, that emotional center of the brain that creates painful feelings. Moreover, there was a reengagement of the rational prefrontal cortex of the brain after sleep that was helping maintain a dampening brake influence on emotional reactions. In contrast, those who remained awake across the day without the chance to sleep and digest those experiences showed no such dissolving of emotional reactivity over time. Their deep emotional brain reactions were just as strong and negative, if not more so, at the second viewing compared with the first, and they reported a similarly powerful reexperiencing of painful feelings to boot.
Since we had recorded the sleep of each participant during the intervening night between the two test sessions, we could answer a follow-up question: Is there something about the type or quality of sleep that an individual experiences that predicts how successful sleep is at accomplishing next-day emotional resolution?
As the theory predicted, it was the dreaming state of REM sleep—and specific patterns of electrical activity that reflected the drop in stress-related brain chemistry during the dream state—that determined the success of overnight therapy from one individual to the next. It was not, therefore, time per se that healed all wounds, but instead it was time spent in dream sleep that was providing emotional convalescence. To sleep, perchance to heal.
Sleep, and specifically REM sleep, was clearly needed in order for us to heal emotional wounds. But was the act of dreaming during REM sleep, and even dreaming of those emotional events themselves, necessary to achieve resolution and keep our minds safe from the clutches of anxiety and rea
ctive depression? This was the question that Dr. Rosalind Cartwright at Rush University in Chicago elegantly dismantled in a collection of work with her clinical patients.
Cartwright, who I contend is as much a pioneer in dream research as Sigmund Freud, decided to study the dream content of people who were showing signs of depression as a consequence of incredibly difficult emotional experiences, such as devastating breakups and bitter divorces. Right around the time of the emotional trauma, she started collecting their nightly dream reports and sifted through them, hunting for clear signs of the same emotional themes emerging in their dream lives relative to their waking lives. Cartwright then performed follow-up assessments up to one year later, determining whether the patients’ depression and anxiety caused by the emotional trauma were resolved or continued to persist.
In a series of publications that I still revisit with admiration to this day, Cartwright demonstrated that it was only those patients who were expressly dreaming about the painful experiences around the time of the events who went on to gain clinical resolution from their despair, mentally recovering a year later as clinically determined by having no identifiable depression. Those who were dreaming, but not dreaming of the painful experience itself, could not get past the event, still being dragged down by a strong undercurrent of depression that remained.
Cartwright had shown that it was not enough to have REM sleep, or even generic dreaming, when it comes to resolving our emotional past. Her patients required REM sleep with dreaming, but dreaming of a very specific kind: that which expressly involved dreaming about the emotional themes and sentiments of the waking trauma. It was only that content-specific form of dreaming that was able to accomplish clinical remission and offer emotional closure in these patients, allowing them to move forward into a new emotional future, and not be enslaved by a traumatic past.
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