每天工作8小时可能导致智商下降，5小时最佳

　　Working more than 25 hours a week could be negatively affecting the intelligence of employees over age 40, according to a study from researchers for the Melbourne Institute of Applied Economic and Social Research in Australia. After conducting reading, pattern and memory tests on more than 6,000 workers, the team determined that working 25 hours a week was the ideal amount of time for cognitive functioning.

　　Working fewer than 25 hours was detrimental to the brain’s agility, while working excessively long hours could cause fatigue or stress, also damaging the brain’s functional abilities.

　　Age 40 is somewhat of a turning point for the brain. Our “fluid intelligence,” or how well we process information, begins its decline around the age of 20, while “crystallized intelligence,” or the ability to use knowledge and experiences, deteriorates starting around age 30. By the time we turn 40, our performance in memory tests and pattern recognition exercises tends to dip off.

　　The researchers are looking into the effect of caretaking on cognitive function in middle age. By age 40, many employees are also taking care of children or a parent or both, creating a job on top of a job. The typical caregiver in the U.S. is a 49-year-old employed female, who spends more than 24 hours taking care of others, the BBC reported. Another factor could be sleep deprivation; high achievers often claim that they can work well on very little sleep.

　　The study noted that the effect of excessive work hours affected both genders equally.

　　澳大利亚墨尔本应用经济暨社会研究所(Melbourne Institute of Applied Economic and Social Research)的一项研究显示，每周工作超过25个小时，会对40岁以上员工的智力产生负面影响。研究团队对超过6,000名员工进行阅读、模式和记忆测试之后确定，每周工作25小时，对于认知功能是最为理想的。

　　工作时间少于25小时不利于大脑的灵敏度，而每周工作时间过长，则会导致疲劳或压力，损坏大脑的功能。

　　40岁是人脑的一个转折点。我们的“流动智力”或处理信息的能力，在20岁左右开始下降，而“晶体智力”或使用知识与经验的能力则在30岁左右开始衰退。到40岁，人类在记忆力测试和模式识别中的表现会出现下滑。

　　研究人员正在研究照料他人对中年人认知功能的影响。到了40岁，许多员工还要照顾孩子或一位甚至两位老人，形成了凌驾于职业之上的工作。据BBC报道，美国的家庭看护者通常为49岁的职业女性，她们要花超过24小时来照顾其他人。另外一个因素可能是睡眠剥夺;许多取得高成就的人往往会声称，他们只需要非常少的睡眠，也可以做得很好。

　　研究显示，工作时间过长对男性和女性的影响没有区别。