Dinosaurs May Have Been Dreamers; Reptiles Experience Same Sleeping Patterns as Humans
A new study reveals that dreaming is not only limited to birds and humans, but also experienced by reptiles.
The study, published in the journal Science, discovered that reptiles also experience the same sleep patterns like the Rapid Eye Movement or REM sleep, and the slow-wave sleep, suggesting that reptiles, even dinosaurs, can also have dreams.
In humans, dreams can occur in REM sleep. During REM sleep the eyes move rapidly, the blood pressure and heart rate rise and the limbs are paralyzed.
On the other hand, slow-wave sleep, also known as deep sleep, is the most peaceful stage of sleep characterized by slow brainwaves and also little dreaming.
For the study, researchers from Germany measured the electrophysiological activity of five lizards called Australian bearded dragons during their sleep by implanting a type of silicon probe in the forebrain region of the lizards. They also observed the eye movement of the bearded dragon while they are sleeping with the use of infrared cameras and computerized video analysis, Huffington Post Reported.
Upon analyzing all the recordings, researchers discovered that the reptiles in the study experienced two phases of sleep: one with low-frequency, high-amplitude brain activity and the other with awake-like brain activity and rapid eye movements, which is like the slow-wave sleep and REM sleep in mammals and birds.
The researchers also discovered that the sleep cycle in lizards is as quick as 80 seconds, while humans usually have sleep cycle between 60 and 90 minutes. The REM and slow-wave sleep of lizards are about the same while the REM sleep is usually shorter than the slow-wave sleep in humans.
Just until recently, researchers believed that sleep stages such as the slow-wave and REM only occur in human. The new discovery suggests that slow-wave sleep and REM sleep must have evolved much earlier than the scientists previously thought.
In a report from New York Times, Daniel Margoliash, a professor of organismal biology and anatomy at the University of Chicago who was not involved in the study, said the study provides "extremely strong evidence that the patterns of structure of sleep that we've seen in a broad range of species is reflective of something that evolved very early in vertebrate evolution and is shared across many - perhaps all - vertebrates."
Even with the discovery of sleep patterns in lizards, the researchers clarified that mammals, bird, and lizards still sleep differently.