Aussie Sleeping Dragons
Here is a fun fact: So it turns out that our very own humble Aussie Bearded Dragons sleep similarly like us!
Researches received quite a surprise when last year they discovered both slow wave (deep sleep) and rapid-eye movement sleep (REM – dream sleep) in these lizards. They observed that brain activity recorded from resting lizards during the night oscillated regularly between these two states of sleep.
What makes this such an interesting find is that up to this point the stages of sleep that characterise human slumber had only been documented in mammals and birds. Now this reptilian Aussie has taken the spotlight in sleep research. It has been argued that slow wave and REM stages of sleep were of relatively recent origin in evolutionary terms as they had not been previously found in more primitive animals such as reptiles. However this research now increases the probability that sleep evolved in all these animals from a common ancestor and some version of staged sleep might exist in animals like amphibians or fish.
The researchers also reported some interesting differences: for example, lizard sleep rhythm is extremely regular and fast: the lizard’s sleep cycle is about 80 seconds long at 27oC, vs. 30 minutes in cat or 60-90 minutes in humans. Also, while in lizards slow-wave and REM-sleep have roughly equal durations during each cycle, REM is much shorter then slow-wave sleep in mammals, and both short and irregular in birds. Overall, lizard sleep seems a lot simpler and may thus be closer to the ancestral mode of brain sleep.
So next time you stumble across one of these dragons snoozing whilst basking in the sun- before disturbing it just remember, how would you like to be woken from a pleasant dream?
Sources:
Bearded dragons show REM and Slow Wave Sleep:
https://www.mpg.de/10477322/reptiles-brain-sleep
