A new study by the National Sleep Foundation has claimed that humans are much shorter sleepers than their closest animal relatives. Primate species sleep for 14 to 17 hours per night, while humans need just seven to nine hours of sleep.

Study co-author David Samson said human species is unique from other when it comes to sleep time. A short and high quality sleep is enough for humans, Samson added. The study included about 21 species of primates to create a database of sleeping patterns. Study researchers used statistical techniques to find a species’ position in primate tree.

According to the study, humans need shorter sleep because their sleep is more efficient than other primate. A quarter of humans’ overall sleep is spend in rapid eye movement (REM), while other primates spend just about 5% of their overall sleep in the deep stage of sleep, the study added. The researchers believe humans’ longer periods in REM could be the major reason why they need less sleep time.

“This evolutionary shift towards shorter, more efficient sleep could be partly due to the transition of sleeping in "tree beds" to sleeping on the ground as we now do”, as per the study. There was a time when humans slept on ground. That time, humans would have had to be more cautious in terms of predators and it had affected sleep time, the researchers believe.

The study also concluded that modern technology has affected humans’ sleep cycles, and hunter gatherers sleep less than people who use modern technology.