Working Memory and Movement – Why Can’t You Run Fast in Dreams?

By on March 8, 2021

Have you ever wondered why you can’t run fast in dreams? Or why you can’t punch properly? If you believe popular “dream interpretations,” you may be given to thinking that it’s a sign of self-doubt or some similar crisis of confidence.

Another theory I’ve seen repeated, is that you can’t run because you are experiencing sleep paralysis. Or because your legs are under a blanket. If either of these explanations are true, then why is it that we can still walk? And maybe fly?

Running endurance training

I have a different explanation. And while this is just a theory, I believe it extrapolates from reasonable science in a logical way; and perhaps sheds some interesting light on the way we thinking normally.

How Our Brain Constructs Worlds

There are actually a lot of things you can’t do well in dreams. Other examples include reading, speaking, telling the time, or tasting food.

Likewise, we often notice huge plot holes in our reasoning. Sure, we’re in a weird jungle… but how did we get there? And why?

All these things may share a common explanation that also explains why you can’t run fast in dreams: working memory.

Dream worlds

Normally, your world is constructed from a combination of sensory input and working memory. We take in a large amount of information through the eyes, ears, muscles, and other sensory organs. However, we can only attend to so much of this information consciously (which is what causes attentional blindness) and a lot of this information comes in at slightly different times.

Your working memory is the architect.

Therefore, it is the job of our brains to “marry” this information in a meaningful way and to fill in the blanks based on our memories and predictions. The “snapshot” of the world you see in front of you right now is a fabrication. A guestimate.

And your working memory is the architect – or perhaps the substrate. This is to say that all this information must be presented somewhere. And this means holding it in memory for a brief spell until the scene is updated by new information.

See also: Cognitive Training – Is Brain Training Effective for Sports, Productivity, and General Performance?

This is why the brain’s seemingly miraculous ability to construct entire worlds during sleep actually makes perfect sense. It’s not that different from what it does during the day!

Why Can’t You Run Fast in Dreams… Or Do Anything Else?

When you are asleep however, there is no sensory input. The world around you is entirely fabricated. The inputs are no longer photoreceptors but random memories and passing thoughts.

But the working memory is limited in capacity and scope. Famously, we can only store 5-to-9 digits at once when trying to remember a phone number.

And so, the worlds of our dreams are similarly impermanent. There is simply too much information here for the brain to keep everything updated and accurate. You can’t read, because in order for you to read, your brain would need to construct a passage of text for you to read from and then maintain it in your mind’s eye as you did.

Why can't you run fast in dreams

We rarely look at our phones in dreams for the same reasons. Our plots lack backstories. And if you look at the clock, turn away, then look back – the time will probably have completely changed.

(It doesn’t help that the language areas of our brains are turned off during sleep, either!)

We can create picturesque scenes because these rely on schemas and stereotypes that exist in multisensory neural maps. But to generate entirely new passages of text or maintain an accurate clock would require a lot more RAM.

The Issue of Running

But this still doesn’t answer the big question: why can’t you run fast in dreams?

My theory is that complex movement also requires a lot of working memory. Think about your own body right now. Where are your feet? Do they feel comfortable?  Where do you feel pressure on them?

See also: The Brain, Movement, and Training

This information is available to you all the time, but you usually aren’t focussed on it. Our attention is limited and so, for the most part, we let our body move reflexively.

Rez

In dreams the same thing happens. You don’t really walk: you instead simply appear places, or accept that you’re moving along with someone else.

But then, when it’s time to run, your brain must simulate the movement of all four limbs. This means maintaining an accurate representation of your body in space. Of every joint. Of the way gravity and the terrain affects that movement.

And you have no feedback from real muscle spindles to help with that process. You have no myotatic stretch response to automatically shorten and contract different muscles.

Is it any wonder you feel uncoordinated and slow?

The same is true when trying to punch, or when trying to drive.

Throw in the fact that our brain calculates speed partly by watching the movement of objects past the eyes (optic flow) and you simply have a lack of information to simulate the experience of running quickly.

And that is, I believe, why you can’t run fast in dreams.

Working Memory and Movement

What’s fascinating about this, is that it underscores an important role for our working memory in movement.

To be able to move gracefully and powerfully, you need to be aware of the positions of countless joints and muscles. You need to marry information from all the senses. And you need to make predictions about how your movements will interact with the environment.

Anything more complex requires intense focus and awareness.

Walking cycles can be outsourced to the central pattern generators. Other basic movements can be handled unconsciously in the striatum. But anything more original or complex requires intense focus and awareness.

See also: Quadrupedal Movement: The Bear Crawl Exercise Explained

And even those unconscious movements can benefit from greater bandwidth. And this is demonstrated nicely by a study that shows how training elderly subjects with verbal and spatial working memory tasks can actually improve their gait cycle (study).

Movement training

This also explains why quadrupedal movements, dance, and advanced calisthenics, can all help to improve your feeling of “place.” Since engaging in more movement-focussed practices, I’ve felt more confident on my feet. More aware of my body. And generally, more connected to my environment. Amazingly, I even move more gracefully in dreams.  

Once again, this shows the indelible link between mind and body. And why we must train both.

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About Adam Sinicki

Adam Sinicki, AKA The Bioneer, is a writer, personal trainer, author, entrepreneur, and web developer. I've been writing about health, psychology, and fitness for the past 10+ years and have a fascination with the limits of human performance. When I'm not running my online businesses or training, I love sandwiches, computer games, comics, and hanging out with my family.

3 Comments

  1. sayian2005 says:

    Hey Adam I had some ideas that I think you would be interested in and I was wondering if you’d like to hear them. Over Email or Instagram you probably are to busy to hear them but still nonetheless it doesn’t hurt to ask ¨I think¨.

  2. Seb says:

    Hey man, great article! Very funny that I have the same thing of not being able to run in my dreams. what I have discovered to overcome this (in my dreams), is running like a lion/leopards on my hands and feet. I’m not even joking, this really works for me. It isn’t as fast as running, but it’s faster than walking. Maybe that’s the fastest speed for my brain to process?

  3. Aiden says:

    Hey Adam, I just wanted to say that personally the way that I have adapted to not being able to run is to kinda float or hop to get from point A to point B

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