Real IELTS Listening Test | Section 4 | The Role Of Sleep In Humans And Animals

[Music] welcome to english listening and vocabulary [Music] section 4 you will hear part of a lecture about the role of sleep in humans and animals first you have some time to look at questions 31 to 40. [Music] now listen carefully and answer questions 31 to 40. good morning everyone in today's lecture i'm going to talk about the role of sleep in humans and animals of all the biological processes in the animal kingdom sleep is perhaps the most important a human can survive for almost two weeks without eating but did you know that one week without

sleep can be fatal it's even worse for animals especially for those who must avoid predators without sleep an animal is much less capable of avoiding an attack this is the case for all animals whether they are reptiles mammals or fish let us look now at how different animals sleep reasons for their ways of rest and the potential problems they might encounter in marine life sleep must be balanced with breathing for example the dolphin must float to the surface as it sleeps in order to breathe like other large sea mammals they keep one eye open and

one half of the brain awake at all times to maintain some amount of consciousness required to breathe and to watch out for possible threats they sleep with only one brain hemisphere in slow wave sleep birds also have unusual sleeping patterns mostly due to being constantly on edge in the presence of numerous predators they usually sleep quite lightly for example swainson's thrush also called olive backed thrush is a medium-sized thrush that takes hundreds of naps during the day each of which lasts just a few seconds while migrating migratory birds tend to function well on micro naps

horses on the other hand do most of their sleeping standing up scientists think that horses developed their habit of sleeping upright as a defense mechanism a way of protecting themselves against predators understanding position keeps a horse in a constant state of readiness to race away if danger should approach also horses do occasionally take short naps lying down horses are heavy animals with big muscles but their bones are surprisingly delicate so lying in one position for a long time could well injure a horse just like humans animals can also have sleeping problems dr john hendricks and

adrian morrison from the school of veterinary medicine university of pennsylvania in philadelphia determined that certain diseases were primarily associated with the sleep states in animals in their research they emphasized that because so much in this area still remains unclear animal models were very important for studies of sleep disorders the physiology of sleep in animals is similar to that of humans but why do we humans sleep researchers and scientists believe it helps us organize our memories of the day that sleep acts as a kind of filing system for the brain without it our thoughts become disorderly

and confused which leads to increased likelihood of accidents and a tendency to say and do bizarre things researchers also believe that sleep plays a key role in learning we sleep so that the brain can integrate new knowledge and form new associations because of the similar sleeping pattern to that of humans rats are often studied in order to increase our knowledge of human physiology in one study rats were kept awake for almost two weeks and their behavior was observed researchers found the sleep-deprived rats could hardly remember anything of what they had been taught that day for

example one rat had been taught to recognize pictures of various parisian landmarks in order to receive food pressing a button below a picture of the louvre would result in food being released and so forth however when deprived of sleep they would press buttons seemingly at random in addition to rats the fruit fly a small insect that feeds and breeds on spoiled fruit also has been used as a model organism and thousands of scientists around the world work on it but why was the fruit fly chosen to be studied it was for practical reasons the most

important one is that the relationship between fly and human genes is so close that the sequences of newly discovered human genes including genes that show a susceptibility can often be matched against their fly counterparts this provides an indication of the function of the human gene and could help in the development of effective drugs to help people with sleeping disorders therefore many scientists today choose to study the genetic structure of the fruit fly which could make a particularly important contribution to the understanding of developmental processes in humans in conclusion sleep is a necessary part of life

not just for humans but for the entire animal kingdom now i'd be happy to answer any questions you may have that is the end of section four you now have half a minute to check your answers [Music] subscribe to the channel for more videos support us by clicking on the like button and leaving your comments here thank you