Getting less sleep has become a bad habit for most American kids. According to a new survey by the National Sleep Foundation, 51% of kids aged 10 to 18 go to bed at 10 pm or later on school nights, even though they have to get up early. Last year the Foundation reported that nearly 60% of 7- to 12-year-olds said they felt tired during the day, and 15% said they had fallen asleep at school.
睡眠不足已经成为大多数美国孩子的坏习惯。根据国家睡眠基金会的一项调查数据，51%的10至18岁的孩子在上学的晚上10点或更晚睡觉，尽管他们必须早起。去年，该基金会报告称，近60%的7至12岁的青少年表示他们白天感到疲劳，15%的人表示他们在学校会睡觉。

How much sleep you need depends a lot on your age. Babies need a lot of rest: most of them sleep about 18 hours a day! Adults need about eight hours. For most school-age children, ten hours is ideal. But the new National Sleep Foundation survey found that 35% of 10- to 12-year-olds get only seven or eight hours. And guess what almost half of the surveyed kids said they do before bedtime? Watch TV.
你需要多少睡眠在很大程度上取决于你的年龄。婴儿需要长时间休息：大多数每天睡18个小时左右！成年人大约需要八个小时。对于大多数学龄儿童来说，十个小时是理想的。但美国国家睡眠基金会的最新调查发现，35%的10至12岁的青少年只有7或8个小时的睡眠时间。猜猜看，几乎一半的受访孩子说他们在睡觉前会做什么？看电视。

“More children are going to bed with TVs on, and there are more opportunities to stay awake, with more homework, the Internet and the phone,” says Dr. Mary Carskadon, a sleep researcher at Brown University Medical School. She says these activities at bedtime can get kids all excited and make it hard for them to calm down and sleep. Other experts say part of the problem is chemical. Changing levels of body chemicals called hormones not only make teenagers’ bodies develop adult characteristics, but also make it hard for teenagers to fall asleep before 11 pm.
“越来越多的孩子开着电视上床睡觉，晚睡也有越来越多的可能，比如很多的作业、上网和手机”，布朗大学医学院的睡眠研究员Mary Carskadon博士说。她说，这些睡前活动会让孩子们兴奋不已，让他们很难平静下来入睡。其他专家表示，部分问题是化学问题。被称为荷尔蒙的身体化学物质水平的变化不仅会使青少年的身体形成成人特征，还会使青少年在晚上11点之前难以入睡。

Because sleepiness is such a problem for teenagers, some school districts have decided to start high school classes later than they used to. Three years ago, schools in Edina, Minnesota, changed the start time from 7:25 am to 8:30 am. Students, parents and teachers are pleased with the results.
由于睡眠对青少年来说是一个很大的问题，一些学区决定高中上学时间推迟。三年前，明尼苏达州埃迪纳的学校将上学时间从早上7:25改为8:30。学生、家长和老师对结果感到满意。