Baby Owls Snooze Like Baby Humans: More Time in REM Sleep

Birds and mammals have more in common that we though--at least when it comes to the science of sleep. It turns out that baby birds have similar sleep patterns to baby mammals and that their sleep changes in the same way while growing up. The findings could lead to a better understanding of sleep-related developmental processes in the brain.

Sleep in both mammals and birds consists of two phases. There's the REM (Rapid Eye Movement) sleep and the non-REM sleep. During REM sleep, we experience our most vivid dreams since that's the point when the sleep cycle is characterized by awake-like brain activity. How long we spend in REM sleep, though, largely depends on how old we are. For example, newborns spend half of their time in REM sleep while sleeping. In contrast, adults only spend about 20 to 25 percent of time in REM sleep.

Birds are the only non-mammalian group that is known to clearly engage in REM sleep. Until now, though, scientists have been unsure whether sleep develops in the same way in baby birds. In order to find that out, researchers examined a population of wild barn owls.

In order to properly analyze these owls, the researchers used an electroencephalogram (EGG) and movement data logger in conjunction with minimally invasive EEG sensors designed for use in humans. This allowed them to record sleep in 66 owlets that varied in age. They made recordings for five days and the owlets showed no signs of having been adversely affected by the study.

So what did the scientists find? It turns out that despite lacking significant eye movements, the owlets spent large amounts of time in REM sleep--like baby humans.

"During this sleep phase, the owlets' EEG showed awake-like activity, their eyes remained closed, and their heads nodded slowly," said Madeleine Scrib of the University of Lausanne in a news release. In fact, just like humans, this REM sleep decreased as the owlets aged.

The scientists weren't just content with these findings, though. They also examined the relationship between sleep and the expression of a gene in the feather follicles involved in producing dark, melanic feather spots. It turns out that the spotting co-varied with a wide variety of behavioral and physiological traits, many of which had links to sleep.

The findings are important for understand both sleep and brain development. In addition, the study shows that pigment also plays a role in sleep. Currently, scientists are planning on studying the science of sleep further, hopefully revealing more about both birds and humans.

The findings are published in the journal Frontiers in Zoology.

Want to see the baby owls sleeping for yourself? You can check out a video of it here.