Sleep Like a Baby Barn Owl
Researchers at the Max Planck Institute for Ornithology (MPIO) and the University of Lausanne have discovered that the sleeping patterns of baby owls appears to change in the same way as it does in humans.
Sleep consists of two phases, REM (Rapid Eye Movement) and non-REM sleep. REM is considered the lightest stage of sleep as this is the point where we experience our most vivid dreams. In addition, a variety of mammals spend more time in REM during the early stages of their lives. For example, newborns spend approximately half of their time asleep in REM whereas an average adult would spend approximately 20-25% in REM.
Consequently, Niels Rattenborg of the MPIO, Alexandre Roulin of Unil, and their PhD student Madeleine Scriba, studied a population of wild barn owls to see if these sleeping patterns hold true for baby birds.
Studying barn owls in the wild, the researchers discovered that this change in sleep is strongly correlated with the expression of a gene involved in producing dark, melanic feather spots, a trait known to covary with behavioral and physiological traits in adult owls. These findings raise the intriguing possibility that sleep-related developmental processes in the brain contribute to the link between melanism and other traits observed in adult barn owls and other animals.
The study shows that despite lacking significant eye movements (a trait common to owls), the owlets spent large amounts of time in REM sleep. "During this sleep phase, the owlets' EEG showed awake-like activity, their eyes remained closed, and their heads nodded slowly", reports Madeleine Scriba from the University of Lausanne. Importantly, the researchers discovered that just as in baby humans, the time spent in REM sleep declined as the owlets aged.
In addition, the team examined the relationship between sleep and the expression of a gene in the feather follicles involved in producing dark, melanic feather spots. The team found that owlets expressing higher levels of the gene involved in melanism had less REM sleep than expected for their age, suggesting that their brains were developing faster than in owlets expressing lower levels of this gene.
Niels Rattenborg from the Max Planck Institute for Ornithology in Seewiesen hopes that "this naturally occurring variation in REM sleep during a period of brain development can be used to reveal exactly what REM sleep does for the developing brain in baby owls, as well as humans."
For more information see the Max Planck Institute.
Sleeping barn owl image via Shutterstock.