If you have a pet pal, chances are that you’ve wondered the same thing at some point. Do animals have similar experiences to us when we dream?
For a long time, animals’ minds and behaviors have fascinated us. Remember Aesop’s fable of The Crow and The Pitcher? Scientists have observed corvids, the family of birds to which crows belong, showing the same behavior noted in that legendary story written nearly 2,500 years ago.
Aristotle even made an interesting remark on animals’ sleeping behavior. In the book The History of Animals, he suggested that, “[…] not only do men dream,” but also “dogs show their dreaming by barking in their sleep.”
Lucretius, a Roman poet, made an observation about his dog sleeping by a fire. He noticed that the dog’s eyes were rapidly moving while his legs twitched, as if he was chasing some kind of imaginary prey in a dream.
We cannot observe an animal’s dreams, but we can predict the sights, sounds or activities occurring in their sleeping minds. This is done by observing how their brain cells fire during “dreaming”, and comparing those patterns to the animal’s waking state.
From koalas who sleep 20 hours a day to dolphins who sleep while keeping half of their brains awake, the animal kingdom is incredibly diverse when it comes to sleep. Research suggests that almost all mammals (including primates like apes and chimpanzees), birds, and even some reptiles experience REM and NREM sleep states.
Scientists have found, by studying the brain patterns of zebra finches, that birds sing songs in their dreams. Rats, like humans, are reported to have dreams about the future, where they might be exploring new places.
When an animal exhibits clear signs of REM sleep, we can say with a reasonable amount of certainty that it might be dreaming.
Now, the question remains, do all animals dream?
Not likely. If there is a lack of neural activity in the brain, any form of mental imagery is unlikely to occur. Thus, for a long time, we believed that animals who do not show evidence for REM sleep, such as insects and aquatic creatures, like fish, cannot dream.
We now have an inkling that some fish or insects may actually dream. In 2022, researchers from Germany and the USA discovered that the jumping spider shows REM sleep patterns, and could potentially dream. They observed that jumping spiders moved their eyes just like dogs do when they sleep.
So, until we explore more, and develop better techniques to measure sleep, there’s no way of knowing what is truly happening inside the brain of a fish as it slumbers!
Humans are not the only species that experiences REM sleep. We have evidence that the brains of many animals follow similar patterns as ours do in deep sleep. Hence, the ability to dream (and inevitably, to have nightmares) is far from exclusive to humans.
