Does The Octopus Have Two Stages Of Sleep?

The color-changing and writhing extremities of the octopus have long been a puzzling mystery to scientists, and one that has been the subject of much previously unfruitful research. But new research suggests that octopus sleep is not just the animal equivalent of hibernation in other animals; it has two stages akin to their human cousins, called “quiet” and “active.”

The theory researchers have been trying to prove is REM sleep has two possible functions for mammals. One is to remove waste from the brain. The other function is to store long-term memories. During this time, humans are said to dream with their eyes moving under closed eyelids while in REM sleep. 

Researchers from the University of Rio Grande in Brazil investigated what is known as “Active sleep” and found that octopuses experience REM-like states when they are asleep. They couldn’t get any information on whether or not these animals dream, but this research offers insight into why humans have so many dreams during Active sleep: because it’s such a similar state! If they do dream, what would they dream about?

To confirm if octopuses were genuinely asleep, the researchers had to test their “arousal threshold,” which is how long it takes them to react. They played videos of crabs outside tanks and tried different stimuli, but none worked because they were fast asleep!

In the future, scientists plan to continue investigating how the sleep of octopi affects their performance when trying to solve and complete various tasks given to them by the researchers. This is important because just like humans who suffer from sleeplessness are negatively affected by it in many ways, so too do they believe that this may be true for octopi.