There’s an old saying that if you think you’re in danger, you might ought to sleep with one eye open.

 

　　Well it turns out that many kinds of birds do just that.

 

　　A group of scientists at Indiana State University studied mallard ducks to learn more about this trait. They filmed a row of ducks while they were sleeping. Sure enough they found that a good part of the time the ducks at the ends of the row kept the eye facing away from the group open, while the eye toward the other ducks closed in sleep. The ducks within the row were more likely to close both of their eyes to sleep.

 

　　The ducks at the ends of the line were actually controlling which side of the brain stayed awake, and which dozed. They were engaging in what scientists call single-hemisphere sleep. The eye controlled by the sleeping side of the brain closed, while the active side kept its eye open and on the lookout.

 

　　You can see how this is good for the group and for the lookout duck as well. The group gets the protection from having someone pulling guard duty, while the guard duck is at least able to get some rest.

 

 

　　睁一只眼睡觉

 

　　有个很老的说法，如果你觉得自己处于危险之中，你会睁着一只眼睡觉。

 

　　事实证明许多鸟类确实如此。

 

　　印第安纳州立大学的一群科学家通过研究野鸭，对它们这个习性有了更多的了解。科学家们在鸭子们睡觉时进行拍摄。果然，他们发现队伍两端的鸭子朝外的那只眼睛长时间睁着，而朝向其它鸭子的那只眼睛闭着睡觉。在队列中间的鸭子们则双眼紧闭睡觉。

 

　　队列两端的鸭子实际上在控制哪边的大脑保持清醒与休息。它们处于科学家们所称的单边睡眠的状态。被睡眠状态大脑控制的眼睛闭上，而被运转状态大脑控制的眼睛睁开放哨。

 

　　这种习性对整个群体及放哨鸭子非常有益。鸭群通过一些鸭子放哨获得保护，而同时放哨鸭子至少能得到一些休息。