Although Santa's reindeer are probably exhausted from their Christmastime antics, reindeer worldwide are gearing up for an entirely different challenge. They have to make it through the long, dark, and bitterly cold Arctic winter. Their counterparts in the north take alternative strategies to survive, such as hibernating and storing fat for future periods of famine. The latter strategy is essential to reindeer survival. A layer of fat that results from overindulgent eating is both sustaining and protective. According to a recent study published in Current Biology, reindeer don't waste time. They can choose to ruminate over their cud while they sleep, as opposed to just eating or sleeping.
The research monitored the physiological processes of four Eurasian tundra reindeer kept in captivity in Norway. Reindeer sleep roughly the same amount during the summer and winter, but during the summer, when food supplies are limited, they must consume significantly more. In order to monitor the reindeer's behaviour during the year's extremes, four days were dedicated to their observation during the summer and winter solstices. When the reindeer chewed their cud, a process known as ruminating, their brains generated waves similar to those in non-REM sleep, according to research using electroencephalography (EEG) brainwave imaging. The deer appeared drowsier as well, less prone to react and more sedated.
The reindeer were able to rest rather than become exhausted from their ruminating. Lead author Melanie Furrer tells Smithsonian Magazine, "I think that's a step further to show, at least indirectly, that sleep during rumination also has a function, and actually that if they sleep there they can save some time and recover brain functions during rumination." Actually, the reindeer are able to spend the valuable feeding time necessary to get ready for each long winter because of their sleeping and chewing habits.
The body of scientific knowledge on sleep is expanded by the discovery of this unique reindeer talent. "We must have an open mind that there are different ways to sleep besides the one that humans do," says Oxford sleep physiologist Vladyslav Vyazovskiy, who was not involved in the study. The conventional perspective holds that you don't eat when you're sleeping. But sleep is not an option in this situation. They have to figure out a cunning way to blend the two, and they do just that. These incredibly gifted animals are undoubtedly an inspiration for efficiency.