toefl対策 [the effects of sleep deprivation]

    How many hours do you sleep in a day? If you sleep less than 6 hours per day, you would highly have a physical and mental illness. Those examples are not only short-term problems such as lost concentration and hallucination but also long-term and serious problems like an increase in the risk of stroke and illness.  
    The first topic is why we sleep. You know it is necessary, but probably don't know the specific reasons. Most people need to sleep for 7 to 8 hours per day. Surprisingly, in the U.S., 35% of adults and 65% of adolescences don't meet the necessary hours of sleep. Short hours of sleep cause a large number of illnesses such as diabetes and high blood pressure, but more closely, it affects less concentration, late physical response, and mood. Most seriously, death would be caused by not enough sleep.
    While sleeping, DNA is repairing. In addition to this, waste products in the brain can be removed. We use energy for walking, thinking, and even breathing. As we take advantage of the energy in a day, adenosine creates waste in our brain and makes us sleepy in the evening. After we sleep, we possibly don't have negative emotions such as being tired and sleepy due to what adenosine and waste in the brain were gotten rid of. Thus, not sleeping for enough hours means waste is still in the brain. If shorter sleeping continues, the waste is going to get bigger and bigger and cause dangerous problems in the future. 
    Researchers and scientists have been still studying sleep and problems, but what we need to do is simply sleep for seven or eight hours a day.