Scientists have disproved the myth that humans are lazy and sleepy: it turns out that humans spend less time sleeping than all other primates. Shorter and more intense sleep helped human ancestors to spend more time communicating and learning new skills, and also allowed the brain to absorb them better. The discovery is reported in the journal Evolutionary Anthropology.
Anthropologists from Duke University have found that people sleep on average seven hours a day, regardless of country and level of civilization. Other primates sleep at least twice as long, some up to 17 hours a day.
In addition, in humans, REM sleep (a phase characterized by increased brain activity, as well as dreams) takes up 25 percent of all sleep time. In other primates, this figure does not exceed 5 percent - the rest of the time they just doze. That is, people were able to stay awake longer and lead an active lifestyle due to the fact that they devote more time to "intense" sleep.
Anthropologists hypothesized that three factors contributed to the transition to more effective sleep: an increased risk of attack by predators in open areas of the savanna (as opposed to trees where other monkeys lived), increased conflicts within the group, and, finally, the benefits of longer communication with other individuals. As it is now, the opportunity to go to an interesting place and meet interesting people was enough for the person to sacrifice part of their dream.
Then, most likely, the basic structure of Homo sapiens sleep was formed: its short duration helped to devote more time to the acquisition and transfer of new skills and knowledge, while the REM sleep phase made possible the rapid assimilation of these skills.