“The closest thing we can say is that animals exhibit some of the same sleep states that humans do.”  

–  Marcus Frank, animal sleep researcher at Washington State University. 

The answer to this question is “probably” and the theories are directly related to the phenomenon of REM sleep and how human sleep cycles play out. However, it is quite difficult to know for sure or to know what they are dreaming of. The research is pretty widespread and basically every animal category you can think of has been studied but, short of a cat telling his owner about his dreams in the morning, it is difficult to nail down the facts.

But, again, everything we do know starts with REM….

REM sleep stage in animals

Humans will spend about 25 years of their whole lifetime sleeping. But, not all sleep is identical. About an hour and a half after people fall asleep, their eyeballs begin to move rapidly around in their sockets.  While the eyes are darting uncontrollably, the body is totally paralyzed but the brain is active as ever.  

In general, mammals and birds all experience the REM sleep stage but cold-blooded creatures do not seem to go through it. For people, this stage of sleep is when dreaming starts and this makes many researchers and scientists wonder whether these cold-blooded creatures dream. 

Over the course of scientific research into this topic, scientists identified REM sleep and them almost immediately started to study animals and whether they experienced this phenomenon. The entire topic of dreams is a mysterious one.

Almost all mammals and birds go through this stage of REM sleep, too. Cold-blooded animals don’t appear to go through REM sleep, though.

But in humans, REM sleep is when dreaming usually begins. Because of this, some scientists think that if animals other than humans dream, it might happen in the REM stage.

Can animals really dream?

So, it is possible that only some animals dream. In 2015, a study showed that lab rats who are exposed to food, will show certain brain cell activity that appears to be the rat mapping out how to get the food. While that implies that dreams have value, many people will attest to the random nature of lots of dreams.. 

In another study, scientists monitored the brain activity of singing bird and found that brain activity when they slept was basically identical.  This may mean they were dreaming about singing or practicing their tune or it might mean that they do no dream at all.  It is difficult to know for sure. Whether or not they see imagery, what they see, what that feels like, etc. is very difficult to decipher. 

Experiences affect dreams

A study by MIT researchers reported in the journal Neuronthat the content of rat dreams is linked to actual experiences. They began by training rats to run along a circular track for a reward.  The reward was food. Their brain activity was monitored during the task and then again later while they slept. 

It was found that while the animal ran the track,  a distinctive pattern of neurons firing in the hippocampus developed. This is a region of the brain known to be involved in memory. There is evidence that animals are recalling their waking life during their sleep hours. 

The researchers realized that the rats moved through various sleep stages, more than 40 REM periods were recorded. Approximately 50 % of the periods were repetitive. The unique signature of brain activity was created during the animals’ waking hours. The correlation was very strong. Moreover, when mammals are divided into prey such as antelope, sheep, etc. Hunters like cats and humans, the hunters usually spend 20 to 35 % of their sleep dreaming. The prey only spends 6 to 8 % of their sleep time spent in dreaming.

The bottom line is that the likelihood is very high that at least some animals dream. However, the way that they experience their dream life is very difficult to know for sure. We are also not quite yet sure why humans dream and our own dream life is a bit of a mystery. But, science is making new discoveries every day…