It seems parents have long been right. Going to bed early is key to getting enough sleep and helping adolescents feel on top of the world, a new study reported。

　　Alack of sleep among youngsters may trigger depression and suicidal thoughts, according to the study by the Columbia University MedicalCenter。

　　"Our results are consistent with the theory that inadequate sleep is a riskfactor for depression, working with other risk and protective factorsthrough multiple possible causal pathways to the development of thismood disorder," said lead author James Gangwisch。

　　"Adequatequality sleep could therefore be a preventative measure against depression and a treatment for depression," he added in the study published in the Friday issue of Sleep magazine。

　　The study followed the nightly habits of some 15,659 college andhigh-school students, and found those who consistently went to bedafter midnight had a 24 percent higher risk of depression than thosewho turned in before 10:00 pm。

　　Night owls also ran a 20 percent higher risk of battling suicidal thoughts, the study added。

　　The American Academy of Sleep Medicine recommends that adolescents should sleep at least nine hours or more a night. Those who were tucked in before 10:00 pm reported they slept on average about eight hours and 10 minutes。

　　But that amount of sleep dropped significantly for those in bed after midnight。

　　And adolescents who slept five hours or less a night were 71 percent more likely to suffer depression and 48 percent more at risk of becoming suicidal, the study said。

　　"It is a common perception and societal expectation that adolescents do not need as much sleep as pre-adolescents, yet studies suggest that adolescents may actually require more sleep," said Gangwisch。

　　"Studieshave found that adolescents do not go to bed early enough to compensate for earlier school start times, and transitions to earlier school starttimes have been shown to be associated with significant sleep deprivation."

　　看来父母们一直以来都是对的。一项最新研究报告称，早睡不仅是得到充足睡眠的关键，而且有助于改善青少年的情绪。

　　这项由哥伦比亚大学医学中心开展的研究表明，青少年缺乏睡眠可能会引发抑郁以及自杀的念头。

　　研究报告的主要撰写人詹姆斯•冈维西说：“有理论认为睡眠不足是导致抑郁的风险因素之一，它与其他风险和保护因素相互作用，通过多种可能的因果途径，造成这种情绪失调。我们的研究结果与这一理论是一致的。”

　　“所以，充足、高质量的睡眠可以成为防治抑郁症的一项措施。”研究报告在上周五的《睡眠》杂志上发表。

　　该研究对15659名大学生和中学生的夜间作息习惯进行了追踪调查，发现那些经常在午夜后就寝的学生患抑郁症的风险比那些在晚上10点前就上床睡觉的学生高24%。

　　研究称，晚睡者产生自杀念头的风险也要高20%。

　　美国睡眠药物学会建议，青少年每晚睡眠时间至少要达到9个小时。晚上10点前就寝的人称他们平均每天的睡眠时间约为8小时10分钟。

　　但那些在午夜后睡觉的人的睡眠时间明显少很多。

　　研究报告说，每晚睡眠时间为五小时或更少的青少年患抑郁症的几率高71%，出现自杀倾向的几率高48%。

　　冈维西说：“目前存在这样一种普遍看法和社会预期，认为青少年不像儿童那样需要那么多睡眠，然而研究表明，事实上青少年可能需要更多睡眠。”

　　“研究发现，青少年上学的时间提早了，但却没有提早就寝来对此加以补偿，而且上学时间提早与严重的睡眠剥夺有关。”