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Sleep Amnesia: Why Do We Forget Our Dreams?

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Do you ever have nights so filled with dreams that you wake up feeling like you haven’t slept at all? I hate nights like that. But what worry me more are the nights when my head hits the pillow and it seems like one minute later, the alarm’s going off and I have no idea where my mind has been for the past eight hours. Everyone experiences dreamless nights at least once in a while, so unless we’re all terrible at remembering dreams, something else must be going on. Does it mean the dreams were too intense for our minds to handle? Is it possible we didn’t dream at all? 


No Sleep Without Dreams
Well, we can rule out one of the aforementioned scenarios. We have dreams every night, whether we remember them or not come morning. According to Scientific American, we have five dreams per night on average, which translates to 1,825 dreams per year. Why we don’t remember all of them is less clear. 


In general, we tend to forget more than we recall. Unless we make a point of writing down our dreams’ content immediately upon waking, chances are we’ll lose at least half of it a few minutes after we start our day. Several theories attempt to make sense of the complexities of dream recall (or lack thereof); most are content based—that is, they propose that something about these forgotten dreams stops them from reaching our conscious selves


A Theory of Repression
When it comes to dream recall, Freud’s theory of repression is by far the most well known. In his book The Interpretation of Dreams, he argues that all dream content is a product of wish fulfillment. So when we don’t remember certain aspects of a dream, it’s our brain’s way of blocking out wishes or longings that we’re not emotionally equipped to handle. Freud also believed that a lack of dream recall signals repression as a form of self-preservation—our brains don’t want us remember certain content because it’s simply too traumatic. And, of course (this is Freud we’re discussing, after all), he felt that most repression (and dream symbols in general) are rooted in sexual desires. 


Alternatives to Freudian Fear
Many other content-based theories besides Freud’s take a crack at dream recall. They also adopt simpler, less psychological stances on the topic. Salience theory, for instance, postulates that we forget some dreams simply because they’re not interesting enough; if nothing remarkable happens in a dream, it’s less likely to stay with us when we wake up. Another theory—this one by L. Strumpell, a dream analyst during Freud’s time—suggests that dream content isn’t organized enough for us to comprehend its events in waking life. However, studies have yet to prove this idea. 


The Mind in Sleep: Psychology and Psychophysiology mentions dream kinesthesia as a potential suspect. It happens when we lose the physical movements in our sleep as soon as we physically move after waking up (such as when we reach for the alarm clock). Another possibility is that our memories are formed through repetition and finding connections to other parts of our lives. So when dreams are especially unique (read: crazy) or too undefined to be relatable, it’s harder to tie them to real-life events and remember them. 


The Brain-Wave Effect
As with so many aspects of dreaming, there’s no definitive answer about what causes dream recall or lack thereof. Some studies have reached a conclusion that supports one view over another. A 2006 study performed at Southern Illinois University at Carbondale and published in the Journal of Clinical Psychology tested Freud’s repression theory against an interference theory (dream kinesthesia falls under this category). The results favored interference theory, but it’s hard to ascribe forgetting dreams to a sole factor. We can’t even limit why we dream at all to a single reason, so it stands to reason that dream recall can’t be simplified that way, either. 


A 2009 Scientific American article entitled “A ‘Complex’ Theory of Consciousness” explores what happens to our thoughts when we sleep. The author, Christof Koch, points out the incongruity between our brains’ being so active during REM sleep (the deep-sleep stage in our sleep cycles) and only vaguely recalling dream details when we awaken, plus the fact that nerve operation doesn’t differ much during that stage from “quiet wakefulness.” However, the brain waves that roll through during deep sleep may impede information processing. This is a more scientific approach to the brain-recall conundrum, but like the other theories, it’s but one possibility of many. 


Regardless, It’s All in Our Heads
Why we forget an entire night’s worth of dreams but remember others is clearly up for debate. However, it does seem like we retain the anxiety-ridden ones more easily. Natalie Angier, a guest on an NPR Talk of the Nation segment that dealt with nightmares and dream interpretation, said that 75 percent of dreams reported in sleep labs and dream journaling have negative content. But, again, that doesn’t support a particular belief—just that we tend to sort out our troubles via dreams. 


I do wonder what I’m missing out on when I wake up without a dream to analyze. I could keep a dream journal or set alarms to wake me up during REM sleep—both of which are shown to improve dream recall. But if the speculation about why we forget dreams is on target, the dreams I don’t remember are either too boring or too terrifying for my brain to hold on to, so maybe I’m lucky to be missing out on those experiences. Perhaps we’re all better off forgetting dreams once in a while—at least it makes the ones we remember that much more intriguing.


Updated October 25, 2010

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