To Dream, Perchance to Forget?

As I awoke on one recent morning, I was fortunate enough (?) to capture the following dream before it vanished:

I was standing at the end of my driveway at dawn talking with my wife, when a skinny bearded neighbor, with his left eye blackened and swollen shut, rode up on a bicycle. He skidded to a stop in front of us, reached down, and snatched one of the three newspapers on the ground at our feet. He then turned and rode back to his house while loudly declaring that now he would not have to buy his own copy. While reflecting on my involuntary generosity, I suddenly connected his facial appearance with the brawl that I had heard at his house the night before.

So, what does my dream mean? Do I secretly think that my neighbors are weird? Am I psychosexually confused? Do I feel unsafe at night? Do I have trouble cancelling subscriptions? Can psychotherapy help?

Standard Perspectives on Dream (REM) Sleep

We generally assume that our dreams serve some positive function. They may allow a glimpse into unfulfilled desires, or provide clues about how to make important decisions, or help solve problems that vex us, or strengthen recently learned information. Much has been written about dreams, with most speculating that dreams play a positive supportive link to psychological health.

Unlearning Theory of Dream Sleep

There is, however, one slightly offbeat perspective which suggests that some dreams have no positive value at all and are best flushed from our consciousness, like mental rubbish. I ran across this position decades ago and would have been inclined to dismiss it, except that it was proposed by Francis Crick, a Nobel Prize winner (along with James Watson) for his discovery of the double helix structure of DNA.

Crick and Mitchison (1983) theorized that, while awake, we form important associations that help us learn about ourselves and our world. However, we also accumulate spurious connections, or random clutter, that needs to be removed from our neural networks. If not disposed of, these parasitic connections can accumulate and hamper the efficiency of our mental activity.

How Parasitic Connections Can Form

Assume, for a moment, that as you begin your day at Starbucks, you notice that the price of your Vente has gone up, then think about inflation, which reminds you of your retirement portfolio, which takes you to whether the job that you just applied to in Miami has a good retirement plan, which makes you think about hurricane season, which nudges you to global warming, which…

The barista calls your name, and you snap back to reality. You then ponder how you drifted from thinking about your caffeine fix all the way to the warming planet in such short order. This unremarkable mental meander—thoughts floating freely from one free association to another—is the stuff that builds the mental clutter composed of parasitic connections.

How Dreams Unclutter Your Memory

Crick and Mitchison argue that such free-form mental activity forms real neuronal connections that eventually need to be cleared away. It is okay to take this random mental walk, but passively storing such connections piles up mental junk that makes efficient thinking more problematic.

Here is how uncluttering works: During REM sleep, your brain sends out signals that activate neural networks formed during the previous day. If important, the links are strengthened. If not, these REM sleep signals weaken the connections. Thus, important associations are reinforced and made more resistant to elimination, while trivial connections (between your coffee and global warming, and linkages in between) weaken and eventually disappear.

Support for the Theory of Dreaming to Unlearn

Crick and Mitchison admitted that this intriguing theory is hard to test, as is the case with many exciting ideas in cognitive science. However, they do provide anecdotal support for their speculation:

• Sleep deprivation. When severely sleep deprived, we are likely to hallucinate because we have not had sufficient REM sleep to clear away parasitic associations. Have you noticed that after pulling a few all-nighters, you have difficulty paying attention in a meeting, or to what your partner is telling you? Crick and Mitchison attribute such distraction to the excess resources that need to be diverted toward holding the parasitic associations at bay.
• Spiny anteater. Consider what would happen if you could never dream. You would need an enormous trash can (cortex) to contain all of the random associations that cannot be flushed away. And one such mammal actually exists: the spiny anteater. Guess how they remain functional? They have an enormous cortex to hold the excess of unnecessary associations.
• REM changes with age. Crick and Mitchison also point to changes in REM (dream) sleep throughout our lifespan. More time is spent dreaming in infancy, when many brand-new and confusing connections are formed and need to be cleared out. We spend about 8 hours in REM sleep during infancy, which declines to around 2 hours in adulthood.

Dreaming Essential Reads

5 Common Recurring Dreams and What They Might Mean

Is It Cheating to Dream About Being With Another Partner?

What About Those Dreams That I Remember?

You may be thinking: Hold on, what about recurrent dreams? We obviously don’t forget those. If you do wake up in the middle of a dream and ponder it, you risk strengthening those wonky associations that your brain may have been trying to undo. Lucky for us, this rarely happens and, if it occasionally does, we can live with some rubbish (like that outdoor barbeque grill that has permanent gunk on it). As a suggestion: If you do awaken at the tail end of a dream, don’t try too hard to capture the dissipating fragments. Just let it go.

Recent Updates of the Unlearning Theory of Sleep

Although proposed decades ago, considerable research supports Crick and Mitchison’s speculation as reasonable and congruent with more recent work in neuroscience (see references, below). As for practical implications of the theory, inefficient REM-related unlearning may relate to PTSD, Alzheimer’s disease, and anxiety disorders (Field & Born, 2017; Poe, 2017), as well as depression and schizophrenia (Gao et al., 2023). A common thread through all of these maladies is difficulty managing problematic cognitions, which may have their roots in parasitic associations.

Closing Thoughts

As for my earlier gem of a dream about my goofy neighbor, it was definitely garbage. Although it provided an entertaining breakfast conversation with my wife, the tale definitely begged to be flushed.

And the next time that a friend wants you to interpret one of their “fascinating” dreams, tell them that their brain may simply have been housecleaning. If they ask who thought of such a dumb idea, just tell them it was a Nobel Prize winner.