Our Better Nature: Do Animals Dream of Coffee and Catnip?

We’ve been fascinated with nighttime dreams since ancient times. And we all dream, even if we don’t recall doing so. Most, but not all, dreams happen during bouts of rapid eye movement, or REM, sleep when our eyeballs dance around in our heads. REM sleep periods occur three to five times per night, each lasting up to an hour. Unless we have certain types of sleep disorders, our muscles are “frozen” — paralyzed basically — as we slumber. This is a good thing, or else we’d be acting out our crazy dreams and nightmares, racking up more injuries than folks who play augmented reality games.

However, there’s no broad agreement as to what purpose dreams serve. Sigmund Freud believed they laid bare our deepest desires, which he tended to think were mainly sex-related. Other dream-theory models include dreams as a means by which we train to fight future adversaries, sources of creativity, or disk-cleanup programs that sort memories. A fairly new theory from an AI programmer is that dreams keep our brains resilient by not focusing too much on what we’re good at in our waking hours.

If we can’t decide what our own dreams are for, perhaps the dreams of other animals can help shed light on ours. It’s clear to pet owners that cats and dogs dream. My own two pups often make cute little whines and yaps as they sleep, their paws paddling as if they could actually catch something in real life. Felines have similar behaviors that signal they dream, too.

In fact, as a result of an old experiment with a rather dark twist, we know what cats dream about. In 1965, two French scientists removed the pons, a part of the brain stem, from several cats. The pons is the area that keeps muscles quiet during sleep, and reactivates them as we wake. The poor cats in the study that lacked this structure got up in their sleep, walked around and acted out normal activities like grooming, as well as aggression. From what the researchers saw, it seemed the cats dreamed about the things they did when they were awake.

In a slightly less ghoulish endeavor, a couple of biologists from the University of Chicago peered at zebra finches’ brains in 1999 and found a parallel. They mapped neuronal patterns while the birds sang during the day, and were able to recognize the same patterns (among others) when the birds were asleep. This meant that part of a finch’s dream-life is spent performing the same melody in their dreams as they sing by day. In 2001, a couple of MIT scientists mapped neurons in rat brains, showing the rats essentially ran the same maze in their sleep that they had learned to run in the daytime.

Lest we conclude that all animals have boring dreams, when chimpanzees catch Z’s, they do some interesting stuff. As researchers remotely watched a group of snoozing simians, they observed them talking in their sleep. I say “observed,” rather than “heard,” because this particular batch of chimps was fluent in American sign language (ASL). While they slept, they routinely conversed with invisible friends. Or perhaps waiters – one chimp was seen making the ASL sign for “coffee,” something it had tasted in the past, along with the sign for “good.” Pretty sure I’ve dreamed about coffee, too.

David Peña-Guzmán, a philosopher at San Francisco State University, says the fact that other animals dream suggests they are self-aware at some level. Peña-Guzmán feels that there must be a self or ego of some kind in an animal that experiences running, barking, drinking coffee, or eating catnip. But Peña-Guzmán does not ask if a dreaming arachnid or other invertebrate has an ego as well.

Maybe it was an idea spawned by pandemic-based boredom, but whatever the impetus, a group of German scientists chose to stay up nights in 2022 and watch jumping spiders sleep. Everyone needs a hobby, I guess. Theirs was to observe 34 slumbering spiders and note every time their eyeballs twitched. The critters’ eyeballs, that is — no doubt it happened to the sleepless spider-watchers, too. To be fair, these were behavioral ecologists, which puts their work in context. Some, at least.

What they found was that spiders really dream. Well, it’s likely they do. Each 17 minutes, the snoozing spiders had short periods of apparent REM sleep, their retinal gyrations easily observed through their translucent lids. In addition, the spiders made small leg twitches and other movements characteristic of dream states. At no other point during the night did the jumping spiders’ eyes dart back and forth in the same manner.

REM-type sleep has also been documented in bearded dragons, based on brain-wave patterns from electrodes that researchers placed in the creatures’ brains. And zebrafish, which clearly live with all kinds of waves, may have sleep stages akin to REM as well, according to their brain-wave signatures. I take heart that although roundworms such as pinworms, heartworms, and other internal parasites may have some form of sleep, scientists are pretty sure they don’t dream.

For about 30 years now, I’ve kept dream diaries – jotting details, or more often snippets, of dreams as soon as I wake. I have no idea if other animal species have rich dream-lives as well; there’s so much we don’t yet know, and absence of evidence is not evidence of absence. But I wouldn’t dream of denying them that possibility.