But one thing that’s always fascinated me is the question of “Do animals dream?” Observing my dogs and cats over the years as they deeply slept, with their paddling legs, twitching ears, and adorable vocalizations, I always believed that of course they were dreaming. But after all this time, I finally decided to do some research to see what science had to say.
Here’s what I found out.
According to Psychology Today, all mammals share the same brain structures that are important in sleeping and dreaming.
Although we certainly can’t ask animals if they dream, fortunately we have the benefit of numerous scientific studies. There are two ways scientists approached this question: first, they looked at animals’ physical behavior during various phases of the sleep cycle. Second, they examined brain wave patterns to see whether the brains of sleeping animals behaved similarly to our own.
What they found was that, just like humans, animals experience alternating phases of brain activity while sleeping. The first stage, called slow wave sleep, is characterized by low frequency electrical brain activity. After about 20 minutes, this is followed by rapid eye movement (REM) sleep, the sleep state associated with dreams.
“Mammals all have the same fundamental sleep cycle,” says Adrian Morrison, DVM, PhD, professor of Behavioral Neuroscience at the University of Pennsylvania Veterinary Center. “During REM sleep, you see the same kind of eye movement, paralysis and twitching across species.”
Scientists have confirmed that the brain wave pattern during REM sleep among animals is similar to humans. Both humans and other mammals display the same level of brain activity and increased heart rate variability during REM sleep. Humans often talk in their sleep, while dogs may “run” or vocalize. Interestingly, platypuses often make movements while they are sleeping that imitate their process of killing crustacean prey before eating it.
So Do Animals Really Dream?
According to numerous researchers, the simple answer is Yes.
In 2007, MIT researchers Matthew Wilson and Kenway Louise trained rats to run through a maze and rewarded them with food. They monitored the rats’ brain activity while they ran and then again while they were asleep. They discovered that while the rats were running, their brains created a distinctive pattern of neurons firing in the hippocampus, the part of the brain involved with creating memories.
The researchers then recorded more than 40 REM episodes while the rats slept and examined the patterns of these same neurons. They found that the neuron firing patterns were identical during both the running of the maze and REM sleep. In other words, it was as if the rats were running through the maze while they slept.
The correlation was so close that the researchers could not only reconstruct the rats’ precise location within their dream mazes and map them to actual spots within the real maze, but they could also determine whether the rats were dreaming of running or standing still. This study was groundbreaking, since it seemed to support the concept of animals’ ability to dream in pictures.
University of Chicago biologists Daniel Margoliash and Amish Dave looked at the brains of zebra finches and discovered something similar.
Zebra finches are not born with their song melodies hardwired into their brains; they have to learn how to sing them. When they’re awake, neurons in the finches’ forebrains called the robustus archistriatalis fire while the birds are singing certain notes. Researchers can determine which note was sung based on the firing patterns of these neurons. By piecing together the electrical patterns of the neurons, Margoliash and Dave were able to reconstruct the finches’ entire birdsong.
Later while the birds slept, the researchers examined the electrical activity in the finches’ brains and discovered that the neurons were not firing randomly; rather, they fired in order, as if the bird was actually singing the song note for note. It was as if the birds were practicing their songs while they slept.
What Happens When Animals Dream?
The newest studies have shown that most animals dream. All mammals appear to dream (although it’s unclear whether dolphins actually do; dolphins have unusual sleep patterns, where they swim slowly in circles while they sleep, using only half their brains at a time.)
Neurobiology research professor J. M. Siegel reports that the smaller the animal, the more the REM sleep. Dr. Stanley Coren, psychology professor at the University of British Columbia, says that dogs go through the same sleep stages as we do, only faster. Little dogs dream quickly and frequently, while bigger dogs dream for longer periods.
Researcher Richard Wilkerson states that birds also exhibit REM sleep. Birds have been known to fly continuously for days, and it’s suspected that they are able to engage in some kind of partial sleep during flying.
Other researchers have concluded that insects and fish don’t experience REM sleep or dreams like birds and mammals do. And as far as reptiles like snakes and lizards? Even though they spend most of their time sleeping, the jury is still out on whether they are actually able to dream.
In one interesting study, researchers claimed that when mammals were separated into two groups, the “hunted” (deer, sheep, rabbits, etc.) and the “hunters” (wolves, cats, humans), the hunters spent about 20-35% of their sleep dreaming. Prey animals slept less, with only 6- 8% of their sleep time spent dreaming. This makes sense when we consider that animals who are vulnerable to predators need to sleep lightly, and remain ready to escape at a moment’s notice.
What If Animals Could Tell Us What They’re Dreaming About?
This may not be as far-fetched as you might think.
Dr. Francine “Penny” Patterson is a world-famous psychologist who has spent years teaching sign language to two gorillas named Koko and Michael. Dr. Patterson has reported that both gorillas have, at different times, described their dreams to her via sign language.
According to Dr. Patterson, Koko has described outrageous events about people and animals right after waking up in the morning. Michael, who is now deceased, had described in vivid detail nightmares he had about his mother, who was killed and butchered in front of him by poachers in the West African bush.
Michael would often wake up in terror during the night. Once, after he awoke in distress, Dr. Patterson videotaped a sign language conversation with him, during which Michael described loud gunshots, fear, cries of pain, and a “cut neck”. He also signed the word for “cry”.
Since these apparent nightmares happened more than once, and always while he was sleeping, it would appear that Michael was actually recounting bad dreams rather than simply describing a memory.
Although no one will ever know for sure whether Michael was really dreaming, the thought of animals having post-traumatic nightmare episodes is truly sobering – and heartbreaking.
Sleep Disorders in Pets
According to veterinarian Kim Smyth, pets, just like humans, can suffer from REM sleep disorders. These disorders happen when the portion of the brain that turns off movement during REM isn’t working properly.
Pets experiencing this scenario may have excessive and sometimes violent movements while dreaming. They may swipe at dream prey and actually launch themselves from their sleeping position to catch it.
Unfortunately, this behavior can cause injury for pets who fall off the bed or couch, or run headlong into walls or furniture. It’s also unsafe for unsuspecting pet parents, who may find themselves an unintended participant in their pet’s dream if they’re sitting too close when it happens!
Medication may help, but Dr. Smyth also recommends considering the use of a padded crate for dogs who experience this disorder to keep them from injuring themselves.
So How Do Animal Dreams Impact Us?
The proof that animals can, and do, have complex dreams and are able to recall sequences of events while they are asleep opens up a whole new set of fascinating questions. Do rats remember re-running mazes in their sleep once they wake up? Do songbirds realize that they’re practicing their songs while sleeping? How do animals distinguish the real world from the one in their dreams?
According to researchers at MIT, research being done on animal dreaming is now being used to study memory disorders like Alzheimer’s Disease and amnesia. It’s also being used to devise ways for humans to memorize facts and learn more effectively.
However, as far as we’ve come in corroborating and studying the dreams of animals, we may never be able to know what it’s like to experience a dream the way an animal experiences it. So it appears, for now, that portion of the question about animals and dreams will have to remain on my list of enigmas.
What do you think? Do you believe that animals dream the way humans do? Tell us your thoughts in the comments below!