Why Humans Need Less Sleep Than Other Animals


Researchers have been looking at the differences in sleep patterns between humans and other animals. Now they have found out that humans need less sleep, but sleep better than other mammals. 21 primate species were studied, including monkeys, chimpanzees  and lemurs.

Human sleep is of higher quality . One of the big differences is the time we spend in REM sleep, a kind of intensive, deep sleep, in which we dream a lot. While, for example, monkeys spend only 5% of their total sleep in REM status, we humans reach 25%, the highest rate of any primate species. According to scientists, REM sleep is good for brain development.

We can get along with about  7 hours of sleep a day, while other  primates need much more. Lemurs, for example, can sleep for up to 17 hours while chimpanzees sleep around 11 hours a day.

Over millions of years of evolution our  sleeping patterns have changed. Our ancestors, millions of years ago, could not sleep as deeply as we do. They  had to spend most of their time in the wilderness and be aware of enemies at all times. The first humans probably slept in trees, where they built platforms to rest properly.

About  2 million years ago the homo erectus left the trees. As they got heavier they started sleeping on the ground where they gathered in groups around fires. They could sleep more deeply because they took turns protecting themselves from enemies around them.

We could  imagine that  street lamps, computer screens and other forms of artificial lighting  are responsible for people sleeping for shorter periods of time, but researchers have found out that this is not necessarily true.



The report shows that hunters and gatherers  in Africa and South America , who don't have that much access to electricity and artificial lighting,  sleep even less than people  in modern societies.



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  • access =  can get easily
  • according to = as said by ...
  • ancestor = here: person who lived millions of years ago
  • artificial lighting = light made by man, not the natural  light of the sun
  • aware = to realize that something exists
  • brain = the organ inside your head that controls how you think, feel and move
  • deeply = intensively
  • development = the way something grows and becomes better
  • electricity = the power that is carried in cables and wires ; it gives us light and heat  and makes machines work
  • evolution = the way that animals and plants change over a period of time
  • gather = get together
  • gatherer = person who lives by hunting and collecting plants and berries
  • imagine = think
  • including = also
  • homo erectus = the first human who could walk upright; he/she lived about 2 million years ago
  • lemur = animal that looks like a monkey and has a long thick tail
  • mammal = type of animal that drinks milk from its mother's body when it is young
  • modern societies = developed areas in the world, where people live in a modern way
  • primate = member of a group of animals that includes humans and monkeys
  • properly = the right way, correctly
  • protect = defend yourself in a dangerous situation
  • reach = get as high as
  • REM = rapid eye movement = period during which your eyes move quickly, when you are dreaming
  • research = when you study a subject in order to find out more about it
  • responsible for = the  reason for
  • sleep patterns = the way we sleep
  • species = group of animals that are like each other and can have babies together
  • status = phase, condition
  • wilderness = large area without any people