Contrary to popular belief, ostriches don't sleep with their heads in the sand. In fact, to all appearances, they never sleep at all: their eyes stay open, although they appear to doze off from time to time. To learn more about the sleep patterns of this unusual bird, researchers captured six ostriches in South Africa and measured their brain wave patterns with data loggers while they slept They expected the brain waves to look like those of other birds and mammals, which cycle between two patterns: deep sleep and rapid eye movement (REM). When the loggers showed that the ostriches were in deep sleep, the birds looked entirely alert. But when they entered another sleep cycle, their heads started to droop. This second brainwave pattern wasn't classic REM, but a unique hybrid of REM and deep sleep patterns, the researchers report this week in PLoS ONE. The only other animal to show this pattern is the platypus, a member of an ancient group of egg-laying mammals known as monotremes. As ostriches are an ancient type of bird, this similarity suggests that the separation between REM and deep sleep may have evolved recently in birds and mammals. One can only speculate on whether ostriches and platypuses have similar dreams, too.和大家所想的不同，鴕鳥睡覺的時候根本不把腦袋放在沙子里。事實上，怎么看，他們都從來不睡覺！他們從來不閉眼睛，雖然它們偶爾看起來困倦的像瞌睡。為了更好的了解這種特殊的鳥類睡覺的形態(tài)，研究者們從南非抓了6只鴕鳥，然后用數(shù)據(jù)測量器測量了鴕鳥們睡覺時的腦電波。研究者們本來期待著看到鴕鳥的腦電波圖像和其他正常鳥類和哺乳類動物相似，就是在兩種樣式：深度睡眠和快速眼動(REM)中循環(huán)的樣子。當(dāng)測量儀顯示鴕鳥在深度睡眠中的時候，這些鳥卻看起來非常警覺！當(dāng)它們進入另一個睡眠循環(huán)的時候，反而開始耷拉腦袋。第二種腦電波也不是傳統(tǒng)意義上的快速眼動，而是一種獨特的快速眼動和深度睡眠結(jié)合的睡眠樣式。研究者們把以上的結(jié)果發(fā)表在了本周的PLoS ONE上面。唯一一種同樣顯示出和鴕鳥類似的睡眠圖樣的動物是鴨嘴獸：一種古老的產(chǎn)蛋類哺乳動物——單孔目動物中的一員。因為鴕鳥本身是一種古老的鳥類，這個相似點暗示了快速眼動和深度睡眠之間的間隔在從鳥類到哺乳動物的過程中有很大的進化。我們只能推斷也許鴕鳥和鴨嘴獸也許會做相似的夢吧。
