Posted by: beagle4 | February 22, 2011

Man’s Best Friend, a dreamer?

The only differences between a human brain and a dog brain are the size and proportion of the brain structures. The average weight of an adult human brain is 1300-1400 grams compared to only 72 grams for a dog (beagle) brain (source). In fact, all mammals have the same basic brain structure. In addition, dogs and other animals experience the same 5 stages of sleep, from slow brain waves to REM sleep (the 5 stages of sleep were discussed in an earlier post). With similar brain structures, it logically makes sense that dogs should have the ability to dream. So my question for the day is, do dogs have dreams? Well more generally, do all animals dream? This is the original article from a blog post written on DreamTree that sparked my interest.

I personally have never been a dog owner (due to my dad’s dislike and hatred of dogs), so I can’t say on a first hand account that I have noticed a dog appear to be dreaming. However, from what I’ve been told, if you ask most pet owners they will tell you that they are certain that their pets have dreams. (Please either confirm this statement or deny it if you are a pet owner). Sleeping pets commonly display dream-like behavior including: twitching eyelids (rapid-eye movement), quivering, facial tics, moving/twitching paws or legs, and barking/growing/snapping noises (similar to how humans talk in their sleep).

An experiment conducted at Massachusetts Institute of technology (MIT) in 2000 by Matthew Wilson and Kenway Louie revealed more insight to the ability of animals to dream. Before this experiment, it was only confirmed that a handful of species, including dolphins and chimps, were thought to have the ability to recall and evaluate a daily sequence of events during dreams similar to the way humans can. (In a previous post I discussed how humans can learn and recall during dreams with the Tetris experiment.) In the experiment, Wilson and Louie trained rats to run through a circular maze track (the finish line contained a reward). Electrodes were attached to the rat’s brains and measured their brain activity while they ran the maze, and also while they slept. The Cambridge scientists studied over 40 different REM recordings of the rats. Half of the rats repeated the neural pattern that was displayed while the rats were completing the maze, and the signature of the brain activity matched/revealed the exact location in the maze the rat was during the dream. The scientists after the experiment were able to conclude that rats experience highly complex dreams involving long sequences of replayed waking events similar to the way humans do. If a rat can have complex dreams, why can’t a dog (the average weight of a rat brain is 2 grams).

The actual scientific article was published in the January 2001 issue of Neuron, a neuroscience scientific journal, and demonstrates the necessity of an education in communicating science. The actual article itself is extremely scientific and complex. With the help of news articles written for the general public, the findings of the experiment are easier to understand (Source 1 and Source 2), however, a lot of the actual scientific explanation/equations are missed.

Without any scientific experimentation, in my opinion the easiest way to find out if animals dream, would be to simply ask them. So why don’t we? Penny Patterson, an ethnologist, did just that. After communicating using sign language with two trained gorillas, Michael and Koko, Ms. Patterson was able to learn about their dreams. Michael was having nightmares of humans killing gorillas, while Koko described events about people and animals (source).

So it appears that mammals that experience REM sleep, experience dreams. However, cold-blooded animals do not appear to experience REM sleep. From this statement, it cannot be concluded that cold-blooded animals do not experience dreams without first creating an experiment and gathering data, but it definitely doesn’t help their chances.

Now just close your eyes and dream…



  1. My dog definitely seems to have them–he does that twitching and yelping thing, like he’s meeting other dogs or chasing rabbits in his dreams. You have me wondering, though, if there’s another explanation. I’ve always assumed it was a dream, and maybe it is, but maybe it’s also something else.

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