While these visions did appear.
And this weak and idle theme,
No more yielding but a dream…."
William Shakespeare, A Midsummer Night's Dream
Each night, visions inhabit our minds during sleep and vanish with the morning light. These visions, these dreams, are without substance. Often, the waking mind recalls dreams only vaguely, if at all. A complete, separate world seems to exist within each of us; a world that can only be found through sleep, through dreams. What are dreams? Why do some people find nightly reverie in the comfort of their beds, while others dread sleep, terrified of the content of their dreams, and yet others recall no dreams to fear or fancy? Speculations on dreams are common and vastly variant. Some people imagine that their dreams are prophetic, while others insist that dreams are merely random firings of neurons. Perhaps a more encompassing view of dreams is appropriate. Neural firing causes dreams, but the randomness of dreams is questionable, since dreams are often correlated with the immediate emotional state of the dreamer. The theories that are presented here do not completely explain dreams. There are many missing pieces to the puzzle of the mind, and our theories on dreaming still have rather large holes.
Dreams occur during sleep. While REM sleep is the best biological condition for dreaming, dreams may occur any time during sleep (1). The brain is less responsive to external inputs while sleeping, engaged, instead, with internally generated input (2) . While responsiveness to external input is greatly reduced during sleep, the brain in not completely unresponsive and can be stimulated by the environment (1) . Thus, external influences can effect dreams. For example, alarm clocks and telephone noises can be incorporated into dreams, as can inputs originating in the body but outside the nervous system, such as the need to urinate. The extent that external activity modifies dreams is difficult to ascertain because the person is often awakened by such activity.
A possible purpose for sleep is that decreased responsiveness allows the brain to undergo "dynamic stabilization," or DS, which is essentially the activation of synapses in neural circuits of the cerebral cortex to enhance and maintain neural functioning (2) . Generally, DS does not initiate the activation of a neural circuit because of extensive inhibition of the motor neurons, and is therefore "non-utilitarian", meaning that there are no visible physical results (2) . DS can occur during consciousness, but the cerebral complexity of warm-blooded vertebrates requires more DS than can occur simultaneously with the processing necessary for waking thought and perception. Sleep thus evolved to provide the brain with a condition virtually free from external distraction (2) .
DS occurs most frequently during REM sleep (2) , which is also the state biologically most suitable for dreams (1) . DS that occurs in the regions of the brain responsible for conscious thought is therefore a possible physiological explanation for dreams. Dreaming could be "a very short-term unconscious awareness" of the DS process that occurs during sleep (2) . Poor recollection of dreams would be expected in this situation, since the brain would have no reason to recall its maintenance process, which is essentially useless information (2) . In this model, dreams are merely a secondary product of other brain activity (2) .
While dreams may not exist for themselves, they do seem to be "quasi-therapeutic" (1) . Dreamers sometimes feel as though a dream resolved a problem or soothed emotional discomfort. The natures of dreams that people recall often reflect their emotional lives at that time (1) . For example, pregnant women often dream about creatures, in anticipation of their coming child (1) . Likewise, dreams often incorporate physical illness (1) .
In dreams, the mind is safe to explore feelings without physically acting (1) . Events or feelings relevant to the present state of the dreamer can be connected with memories of events and feelings, thus integrating the current events into the emotional life of the dreamer (1) . This is most evident in instances of trauma, when the dominant emotion of the dreamer is most apparent (1) . Dreams after trauma generally follow a pattern (1) . First, the trauma is replayed through the dream, sometimes recreating the actual event, and sometimes depicting another trauma that elicits similar reactions. Then, dreamers often experience "survivor's guilt", the feelings of uncertainty about blame. As the trauma is connected to other memories of the dreamer, dreams return to their previous patterns, if the dreamer heals emotionally (1) . If the dreamer is unable to recover successfully, terrifying dreams may continue as a symptom of Post-Traumatic Stress Syndrome (1) .
The essential component of dreaming is connecting; dreaming connects things and feelings in a way that waking thought does not (1) . Waking thought is generally more directed and goal-oriented. In contrast, dreams lack direction. Waking thought is like a motor boat on a wave of emotion. While emotion definitely influences the course of the boat, the boat can be guided with conscious effort. Dreams are more like rafts that drift through emotional waves, guided by the emotional current rather than any conscious effort. The thought processes of sleep are not guided by as many inhibitory signals as the thought processes of the waking mind.
Both approaches are scientific in nature, using observations to guide conclusions. The first explanation for dreams focused on the physiological causes of dreams. In essence, dreams are caused by firings of the neurons in the brain, re-establishing a chemical balance. The second explanation for dreams consisted of psychological effects of dreaming. Dreaming settles emotional disturbance, integrating current feelings with memory. While our understanding of dreams is still incomplete, these two pictures of dreams compliment each other well. Both models essentially maintain homeostasis in the mind, chemically and emotionally. Since chemicals determine emotion, both models say the same thing, but in different ways.
2) Sleep and Memory: Evolutionary Perspectives , J. Lee Kavan
| Course Home Page
| Back to Brain and Behavior
| Back to Serendip |