Ever wonder why your cat sleeps all day while you're stuck with the measly seven hours you can cram in between Scandal and your morning commute? As it turns out, you're just way better at sleeping than your furry friend. According to a study in Evolutionary Anthropology, humans evolved to be the most efficient sleepers in the primate family. Researchers from Duke University studied the sleep patterns of 21 primate species and hundreds of other mammals, according to a press release. They found humans sleep less than most primates—the sleepiest of which gets as much as 17 hours per night. But humans also sleep deeper than other animals, with 25% of our shuteye coming as REM sleep; some primates get as little as 5%.
Researchers hypothesize that when our ancestors came down from the trees, a change in sleep patterns proved beneficial, Medical News Today reports. Less time spent sleeping on the ground meant less time to be eaten by a lion or attacked by a rival tribe and more time for social interactions and other benefits. "Less sleep would enable longer active periods in which to acquire and transmit new skills and knowledge, while deeper sleep may be critical for the consolidation of those skills, leading to enhanced cognitive abilities in early humans," the study states. So—as Gizmodo puts it—the fact that we're "burning the candle at both ends" might explain "why humans are playing with iPads while the rest of our close family is still throwing poop." (In fact, another study shows ancient humans may have slept even less than we do now.)