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Scientists are unclear as to why we sleep. Does it facilitate only rest, or is sleep the precursor to something more? After observing the sleeping patterns of several animals, scientists found that all mammals sleep.
One theory is that sleep acts as a mechanism for protection, as this way animals can keep still and become less noticeable to predators at times when they are especially vulnerable, like during the night. However, when sleep patterns of different animals were compared, it was noticed that different animals have different lengths of sleeping time. For instance, dolphins and whales do not sleep for very long, and keep moving even when they are asleep. Giraffes also spend no more than 20 minutes asleep. In general, animals that serve as food for other animals sleep the least.
Another theory is that we sleep to enable the muscles and the brain to recover from the fatigue of a busy day. Again, however, research has disproved this. Scientists doing research about the activities of the brain found that even a sleeping brain is far from idle!
Brain patterns taken during sleep show that the brain goes through two different phases of sleep. In the first phase, there is fast activity within the brain, and the eyes move rapidly. It is in this phase that we dream ? this is called REM or rapid eye movement sleep. In the second stage, the brain records and sifts through the knowledge it has gathered all day. This is called NREM or non-rapid eye movement sleep. NREM comprises four stages of sleep and during an eight hour sleep period, the brain goes through all these different phases of sleep about four to five times.
Sleep patterns change as people age. Infants spend more time sleeping and have more REM sleep compared to older children and adults. For example, newborn babies sleep about 16 hours per day and spend 50 per cent of that time in REM sleep. Older people (50-85 years old) sleep only 5.75 to 6 hours per day and spend 13.8 to 15 per cent of that time in REM sleep The ?average? human sleeps about eight hours a day. That?s one third of your life! In other words, you sleep for about 122 days every year. A 75-year-old person would have spent a total of about 25 years asleep!
One theory is that sleep acts as a mechanism for protection, as this way animals can keep still and become less noticeable to predators at times when they are especially vulnerable, like during the night. However, when sleep patterns of different animals were compared, it was noticed that different animals have different lengths of sleeping time. For instance, dolphins and whales do not sleep for very long, and keep moving even when they are asleep. Giraffes also spend no more than 20 minutes asleep. In general, animals that serve as food for other animals sleep the least.
Another theory is that we sleep to enable the muscles and the brain to recover from the fatigue of a busy day. Again, however, research has disproved this. Scientists doing research about the activities of the brain found that even a sleeping brain is far from idle!
Brain patterns taken during sleep show that the brain goes through two different phases of sleep. In the first phase, there is fast activity within the brain, and the eyes move rapidly. It is in this phase that we dream ? this is called REM or rapid eye movement sleep. In the second stage, the brain records and sifts through the knowledge it has gathered all day. This is called NREM or non-rapid eye movement sleep. NREM comprises four stages of sleep and during an eight hour sleep period, the brain goes through all these different phases of sleep about four to five times.
Sleep patterns change as people age. Infants spend more time sleeping and have more REM sleep compared to older children and adults. For example, newborn babies sleep about 16 hours per day and spend 50 per cent of that time in REM sleep. Older people (50-85 years old) sleep only 5.75 to 6 hours per day and spend 13.8 to 15 per cent of that time in REM sleep The ?average? human sleeps about eight hours a day. That?s one third of your life! In other words, you sleep for about 122 days every year. A 75-year-old person would have spent a total of about 25 years asleep!
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