A lack of sleep can easily make a child cranky, irritable or unfocused. But can it make your elementary-school child more likely to be depressed or even delinquent?

In the latest in a series of expert warnings about the high cost of sleep deprivation, a new study of 140 elementary-school students suggests that it can. Among these third- through fifth-graders, poor sleep was linked with more aggression and delinquency, as well as a higher incidence of depression, anxiety and low self-esteem. The study appears in the latest issue of the journal Child Development.

All the kids in the study tended to have more emotional and behavior problems when their sleep was impaired. But the effect was largest among children under stress, such as those from poor families. In contrast, when the kids in poverty got enough sleep, their behavior tended to fall near a normal range, according to the study, led by Mona El-Sheikh of Auburn University. Sleep problems were defined in the study as short sleep times, restlessness, frequent awakenings, or irregular sleep schedules. Measurements were taken by wrist monitors worn by the child, as well as parent questionnaires and child interviews. The children were followed for two years.

Similar emotional effects have been found in older kids. A Columbia University study linked lack of sleep among teens to a 24% higher rate of depression, and a 20% higher rate of suicidal thinking. The study was unusual in showing that the lack of sleep, which alters the brain's response to stress, may actually cause sadness and thoughts of suicide, rather than simply being another symptom of depression.

Sleep loss also has academic effects. We've posted before on research showing that getting enough sleep tends to improve kids' grades. Other research suggests a lack of sleep may affect small children's brain development.

As we've written before, ensuring that your kids get the recommended allotment of sleep can take a massive effort when both parents are getting home fairly late in the day-and there needs to be time for settling in before bed. Sometimes hitting that 7 of 8 p.m. bedtime for younger kids is just impossible when parents don't even get home until 6.

Readers, do you see more behavioral problems in your children when they lose sleep? Do they have a tougher time emotionally? How do you find time to get your children settled for adequate sleep amid other pressures of the juggle? Any advice for getting your kids off to bed early during the work week?

Sue Shellenbarger

• series [´siəri:z] n.连续；系列；丛书 (初中英语单词)
• expert [´ekspə:t] n.&a.专家；内行 (初中英语单词)
• depression [di´preʃən] n.沮丧，抑郁；萧条 (初中英语单词)
• anxiety [æŋ´zaiəti] n.挂念；渴望；焦虑的事 (初中英语单词)
• journal [´dʒə:nəl] n.日记；日报；杂志 (初中英语单词)
• emotional [i´məuʃənəl] a.易动感情的；情感的 (初中英语单词)
• stress [stres] n.强调；压力 vt.强调 (初中英语单词)
• contrast [´kɔntrɑ:st] n.对比 v.使对比(照) (初中英语单词)
• poverty [´pɔvəti] n.贫穷(乏，瘠)；不足 (初中英语单词)
• normal [´nɔ:məl] a.正规的 n.正常状态 (初中英语单词)
• frequent [´fri:kwənt] a.常见的，频繁的 (初中英语单词)
• columbia [kə´lʌmbiə] n.哥伦比亚 (初中英语单词)
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• adequate [´ædikwit] a.足够的；适当的 (初中英语单词)
• behavior [bi´heiviə] n.举止，行为 (高中英语单词)
• irregular [i´regjulə] a.不规则的；不正当的 (高中英语单词)
• response [ri´spɔns] n.回答；响应 (高中英语单词)
• sadness [´sædnis] n.悲哀；悲痛；凄惨 (高中英语单词)
• suicide [´su:isaid, ´sju:-] n.&a.自杀(者)(的) (高中英语单词)
• symptom [´simptəm] n.症状，症候 (高中英语单词)
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• academic [,ækə´demik] a.学术的 n.大学学生 (英语四级单词)
• bedtime [´bedtaim] n.就寝时间 (英语四级单词)
• irritable [´iritəbəl] a.急躁的；过敏的 (英语六级单词)
• depressed [di´prest] a.消沉的；萧条的 (英语六级单词)
• auburn [´ɔ:bən] n.&a.赭色(的) (英语六级单词)