Catching Zzz’s and Grubbing: Reindeer Master the Art of Sleepy Snacking

Bhumika Goel / December 2023

The holiday season for arctic reindeer is no exception to multitasking. A new study suggests that reindeer can eat while sleeping. This timesaver strategy, as described in Current Biology on December 22, is an ingenious way for animals to catch some catnaps under harsh conditions.

Summers are more hectic for Arctic reindeer. When food is plentiful, reindeer graze for extended periods of time. Chewing the regurgitated food makes it smaller and easier to digest. The summer food festival divests the reindeer of its sleeping time. But reindeer cannot let go of slumber time and doze over chewing.
Neuroscientist Melanie Furrer and chronobiologist Sara Meier studied reindeer sleep patterns. They taught reindeer (Rangifer tarandus tarandus) to tolerate a pen and electrodes on shaved skin to test if reindeer might genuinely eat while they slept. According to Meier of the University of Zurich, reindeer treat lichen like candy. The procedure entailed some kicks and lots of lichen goodies.
The researchers were looking for the brain waves that appear during non-REM sleep, a deep, restorative sleep phase. These waves appeared when the reindeer were chewing cud, though the chewing motion made it hard to say whether the signal was identical to regular sleep session.

It was hard to study the brain waves because munching activity disturbs it, says Furrer, also of the University of Zurich.

The deep, restorative stage of non-REM sleep is when the brain waves appear. These waves were visible during the munching process by reindeer. Scientists study the other significant signs pointing to sleep while chewing. The reindeer were calm while chewing, often with their eyes closed.
Reindeer were in a very relaxed state that resembles the body position of non-REM sleep, Furrer says. Ruminating reindeer remained undistracted, even from other rustling neighbors. Reindeer require catch-up recovery sleep when they are kept awake. However, the researchers discovered that the amount of time spent chewing reduced the amount of recovery sleep.

Neurobiologist Niels Rattenborg of the Max Planck Institute for Biological Intelligence in Seewiesen, Germany, who was not involved in the study, says that strands of evidence “convincingly demonstrate that reindeer can sleep while ruminating.”

The reindeer exhibit evidence of sleeping with both sides of their brains while chewing, compared to fur seals, ducks, and long-haul flying frigatebirds. It would be intriguing to discover how precisely reindeer manage this, according to Rattenborg. Researching different types of sleep could shed light on people’s sleepwalking, “a poorly understood and potentially dangerous sleep disorder,” according to him.

Neuroscientist and study coauthor Gabi Wagner says that Indigenous reindeer herders believe in a system known as “pasture peace.”

“To be quiet and have peace, to ruminate, reindeer require time and space,” according to Wagner of the Norwegian Institute of Bioeconomy Research in Tromso. “For the first time, this paper demonstrates that there is a genuine physiological need to have enough quiet to ruminate without interruption to meet the requirements for sleep.”

Bhumika Goel is a technology and design thinker, a lifelong learner having a wide range of experience across WordPress development, content marketing and search engine optimization. Creative web applications, tools, and products that your customers will love and get you real business results, is something she can empower you with. She is passionate for delivering high-quality work that meets the needs and expectations of her clients. She is always eager to learn new skills and technologies to enhance her portfolio and stay ahead of the curve. She is looking for new opportunities to collaborate with other professionals and help businesses grow their online presence and reach their goals.