During adolescence, the body goes through many changes and these include a shift in sleep patterns. Researchers from MIT have been tracking the body?s need for sleep in teenagers. They found that though adolescents need as much as 9.5 hours of sleep a day, they get to bed later and later with each passing year. In fact, the sleep cycle shifts later by as much as 12 to 18 minutes each year between the ages of 10 and 20! So by the time a 10yearold who sleeps at 8 pm grows to be 17 or 18, his body naturally wants to stay up till 10:30 pm or 11 pm.
According to researchers, this is because of a hormone called melatonin (褪黑激素) that is secreted (分泌) by the pineal gland — a tiny structure deep inside the brain. Melatonin regulates the body’s natural daynight rhythms. It causes a person to become sleepy by lowering his body?s core temperature. In teens, melatonin is secreted much later in the evening and continues to increase throughout the night. This makes it difficult for teens to fall asleep earlier as they did in their younger years. Likewise, the effect of melatonin continues until much later in the morning, making it hard for them to wake up early.
A study found that at least one in four teens is tired and falls asleep in school at least once a week. During sleep, important body functions and brain activities happen. So how can teenagers get their sleep enough? The American Academy of Pediatrics (AAP) recommends that middle and high schools should start later — not before 8:30 am. This should give teens some more time to sleep at night.
【2017届高考英语一轮复习技能提升练:选修8 Unit 2《Cloning》(新人教版含解析)】相关文章:
★ 【课堂新坐标】2017届高考英语(通用版)二轮复习书面表达专题训练:技法2 引人入胜的开篇语(含解析)
★ 【课堂新坐标】2017届高考英语(通用版)二轮复习书面表达专题训练:训练3 书信、邮件+议论文(Ⅰ)(含解析)
★ 2017高考四川省广安市英语阅读理解一轮系列训练:22(含解析)
★ 【优化方案】2017届高考英语二轮复习全国卷Ⅱ题型重组训练:第11组(含解析)
★ 2017届高考英语(江苏专用)二轮复习高考单词5大记忆法课件:4.联想记忆法
★ 2014届高考英语一轮复习课时作业(三十二)选修6Module 2《Fantasy Literature》(外研版)
★ 【课堂新坐标】2017届高考英语(通用版)二轮复习书面表达专题训练:训练6 议论文+记叙文(含解析)
★ 【人教版】2014届高考英语一轮复习指导考点针对练:必修1 unit4《Earthquakes》
最新
2017-04-24
2017-04-24
2017-04-24
2017-04-24
2017-04-21
2017-04-21