pulling a late-nighter? you might not want to reach for the sugary snacks to keep you awake. a new study involving fruit flies suggests the sleep-deprived mind is kept alert by hunger。

　　the study examined the effects of starvation on fruit flies that had been genetically engineered to be sensitive to sleep deprivation. sleepy flies deprived of food stayed awake longer than sleepy flies that got meals. the starving flies also lived longer。

　　"from an evolutionary perspective, this makes sense," said study co-author matt thimgan, a washington university postdoctoral researcher. "if you're starving, you want to make sure you're on the top of your game cognitively, to improve your chances of finding food rather than becoming food for someone else."

　　to tease out the relationships between sleep, starvation and survival, the researchers deprived fruit flies of both food and sleep. they found that starving fruit flies spent more time awake than satiated flies did. the researchers also tested the flies' saliva for enzymes that signal sleepiness and measured the flies' ability to associate a light with an unpleasant stimulus. both tests showed that the starving flies were alert, not sleepy。

　　the starving flies also survived up to 28 hours without sleep, three times longer than the flies with access to food. the survivors' ability is probably linked to a gene that helps the fruit-fly brain manage the storage and use of fat molecules, the researchers said。

　　美国“趣味科学”网站8月31日文章：克服疲倦的新方法：饥饿

　　需要熬夜怎么办？你可能不想靠吃甜点来赶走睡意。对果蝇的最新研究表明，饥饿能让缺少睡眠的头脑保持清醒。

　　研究测试了经过基因改造从而对缺少睡眠特别敏感的果蝇挨饿后的反应。结果发现，相比那些得到食物的困乏果蝇，饥饿的困乏果蝇清醒的时间更长。同时饥饿的果蝇寿命也更长。

　　“这从进化的角度看是行得通的，”研究作者之一、华盛顿大学的马特说道。“如果你处在饥饿状态，你就会努力设法清醒地掌控自己的生存状态，以增加寻获食物的机会，而不是成为别人的食物。”

　　为了找到睡眠、饥饿和生存之间的关系，研究人员同时剥夺了果蝇的食物和睡眠。他们发现，饥饿的果蝇比吃饱的果蝇清醒的时间长。研究人员还检测了果蝇唾液中显示困倦程度的酶，还测试了果蝇将光亮与令人不快的刺激联系起来的能力。两种测试结果均表明饥饿的果蝇是清醒的，没有睡意。

　　饥饿的果蝇能在不睡觉的情况下存活28小时，是那些能得到食物的果蝇存活时间的三倍。研究人员称，这种生存能力可能与帮助果蝇大脑控制脂肪分子存储与使用的一种基因有关。