Scientists see surprising brain activity in sleeping octopuses that could mean they dream like us

• Scientists observed sleeping octopuses and saw their brains enter a deep sleep like ours.
• This deep sleep is similar to a dream state in mammals, so octopuses may also dream.

You may not have noticed, but when you're deep in a dream you probably twitch, toss, and turn as your brain shifts to a more active state.

Turns out, you're not so different from how an octopus sleeps, according to a new study published in the journal Nature on Wednesday.

For the study, scientists spied on multiple sleeping octopuses. They witnessed brief, recurring cycles where the cephalopods twitched and flashed brilliant rings of color across their pigmented skin.

To get an even clearer picture of what was going on, the scientists inserted probes to study the octopuses' brains during this sleep stage as well as other stages of sleep and wakefulness.

By studying the octopus's brain activity, the team found that these cephalopods have similar active and quiet sleep cycles to us mammals and that certain periods of their active stage resembles rapid eye movement sleep.

REM sleep is often when humans dream, leading scientists to wonder if octopuses may dream like us.

Octopuses and humans are separated by about 600 million years of evolution

The last common ancestor to cephalopods and humans lived some 600 million years ago, according to Medium. Therefore most scientists believe these aquatic animals function very differently from us in most respects.

But what researchers found in this new study is that the way we sleep is quite similar to an octopus.

"The fact that two-stage sleep has independently evolved in distantly related creatures, like octopuses, which have large but completely different brain structures from vertebrates, suggests that possessing an active, wake-like stage may be a general feature of complex cognition," Leenoy Meshulam, co-author and theoretical physicist at the University of Washington School of Medicine and the UW Computational Neuroscience Center, told New Atlas.

To understand octopus sleep, the team examined the electrical wave patterns they recorded when the animals were awake and asleep. They found that the patterns were similar when the animals were experiencing REM-like sleep compared to when they were awake and engaged.

That data combined with the changes in their skin color during this sleep stage led the scientists to suggest that the octopuses could be recreating memories of wakefulness while sleeping, aka dreaming. Or, they suggested, it could be them running drills to practice their camouflaging skills while sleeping.

They can't know for sure whether it's the former or the latter. It is hard to ask an octopus about its sleep quality after all.

Even so, no matter how alien they may look, studies like this are a good reminder that we may share more similarities than differences.