Scientists in Brazil said an octopus' wild shifts in color, behavior, and movement serve as evidence of a sleep cycle — suggesting the octopus pivots between active and quiet sleep, just like humans shifting between deep and REM sleep, according to a new study published in the journal iScience.
Octopuses may dream, and shift colors like an electric frenzy
The octopus was observed to wrap itself with eight legs in a self-hug, its eye pupils focused into a thin slit, while it breathed evenly in a whiteish-gray color. But in seconds, it experiences frenzied shifts in color between a rusty red and a singed orange — as its eyes, muscles, and signature sucker pads twitch like it's having a visceral, intense dream.
The new study further shows how sleep could have evolved similarly in vastly different creatures — hinting at the possibility of something like REM sleep in octopuses. REM sleep stands for the rapid eye movements humans experience in a specific state of sleep.
"It is not possible to affirm that octopuses dream because they cannot tell us that, but our results suggest that during 'Active sleep' the octopus experiences a state analogous to REM sleep, which is the state during which humans dream the most," said Sylvia Medeiros and Sidarta Ribeiro — both study authors — in a CNN interview.
A Professor of Neuroscience at the Brain Institute of the Federal University of Rio Grande do Norte, Ribeiro was joined in the study by Medeiros — a doctoral student of the same institution. In the past, scientists thought only mammals and birds had varying levels of sleep — like a sleeping dog kicking its legs like it's chasing a dream-rabbit. However, later research showed that some cuttlefish and reptiles — including another cephalopod and relative of octopi — also exhibit both non-REM and REM-like sleep states.
While Octopuses have vastly different brain structures than humans, they still share some similar functions to human brains. They possess special learning capabilities — like solving problems and other high-order cognitive skills, explained the authors. Additionally, sleeping octopi serve as a "vantage point" for compare-and-contrast studies of the neurobiological and psychological structures between mammals. The similarities in sleep patterns are probably because of "the very taxing mental loads experienced by these separate group of mammals," said the authors, according to the CNN report.
Octopus dreams would be 'GIF-like,' if they have them
To ensure they were studying sleeping octopuses — and not just ones resting their eyes, the researchers captured videos of four octopus insularis species alive in their lab, looking at the creatures' behavior over a timeframe of more than 50 days. While awake, the octopuses were acutely aware of very weak stimuli, but in both sleep states, it took intense visual or tactile stimuli to elicit a behavioral response, according to the scientists.
Typically, octopuses alter their color for communication or camouflage purposes — but while asleep, the only environment available to trigger frenzied shifts in color must come from within the animals. Inferring the changes were caused by independent brain activity, the researchers discovered how the octopi enter active (or REM-like) sleep after a long period of quiet sleep — which takes about six minutes for the eight-legged creatures.
"If octopuses indeed dream, it is unlikely that they experience complex symbolic plots like we do," said the authors to CNN. "'Active Sleep' in the octopus has a very short duration (typically from a few seconds to one minute. If during this state there is any dreaming going on, it should be more like small videoclips, or even gifs."
It seems mammals and birds aren't the only ones who can dream, with octopuses possibly experiencing GIF-like dreams of their own. While there's no way to understand how octopi perceive their dreams, or what they think of them — perusing a social media site's best GIFs could be a distant analog of the mysterious animals' underwater dream world.
This was a breaking story and was regularly updated as new information became available.