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 p.m. grows to be 17 or 18, his body naturally wants to stay up till 10:30 p.m. or 11 p.m.
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 a.m.. This should give teens some more time to sleep at night.
【【金版教程】2017高考英语二轮复习训练:3-1-1 词性转换b(含解析)】相关文章:
★ 【三维设计】2017届高考英语(江苏专用)二轮复习写作增分锦囊课件:6 书面表达常见错误及对策
★ 安徽省淮南市2014高考英语一轮单项选择及文章训练(23)及答案
★ 【人教版】2014届高考英语一轮复习指导考点针对练:必修1 unit2《English around the world》
★ 2017高考四川省广安市英语阅读理解一轮系列训练:4(含解析)
★ 常熟市2014高考英阅读理解语一轮(暑假)训练题(6)及答案
★ 【三维设计】2017版(江苏专用)二轮复习练习:必修2 Unit 2《Wish you were here》单元检测(含解析)
★ (安徽专用)2014届高考英语一轮复习方案 作业手册(24)模块8 《Unit 24 Society》(含解析) 北师大版必修1
★ (安徽专用)2014届高考英语一轮复习方案 作业手册(14)模块5 《Unit 14 Careers》(含解析) 北师大版必修1
最新
2017-04-24
2017-04-24
2017-04-24
2017-04-24
2017-04-21
2017-04-21