英语学习网站在动画或是漫画中，我们经常可以看到一连串的“Z”表示一个人处于深度睡眠状态。你有没有好奇，字母“Z”是怎么和睡觉联系在一起的呢？
In cartoons and comics, it’s not uncommon to see a series of Z’s to indicate that a person is in deep slumber. How does the letter “Z” come to be associated with sleep?
关于“Zzz”的由来，有很多种解释。“Zzz”是打鼾声的拟声词（onomatopoeic words），在1918年美国方言协会的方言笔记中首次出现，用以表示嗡嗡声或呼噜声。
American Dialect Society’s Dialect notes, Volume 5, 1918:
z-z-z (buzzing, or snoring)
也有说法称，“Zzz”与锯木头时形成的“Z”形和发出的声音有关。美国早期的动画经常用锯子切割木头来代表睡眠。在美国，“锯木头”也是打鼾的一种说法。
It is also related to the Z-shape and snoring sound made when someone saws wood. In fact, early cartoons often continued to show a saw cutting through a log to represent sleep. In America, to “sawing logs” or “sawing wood” is a term for snoring.
俚语常以zizz指睡觉，作名词、动词都可以。例如：
He felt refreshed after a good zizz.
好好睡了一觉后，他感到神清气爽。
在英国，“catch some zeds”也被用来表示睡觉。
关于睡眠，还有很多种其他的表达。
Fall asleep
Fall asleep侧重“无意识/不刻意地入睡、自然而然入睡”的含义。与be asleep 相比，前者更强调入睡的动作，后者指入睡的状态。
Snooze
Snooze作为非正式表达，可以指在白天的小睡或打盹儿。
Snooze: (informal) to have a short light sleep, especially during the day and usually not in bed.
Nap
Nap和snooze类似，也指白天的小睡、打盹儿。例如午后小睡就是take a nap after lunch.
Doze
Doze 指短时间、较浅的睡眠。
Doze: to sleep lightly for a short time
For your safety, don’t doze off while driving.
为了你的安全，开车时千万别打瞌睡哦。
Drowse
Drowse表示将睡未睡、迷迷糊糊的状态。
Drowse: to be in a light sleep or almost asleep
drowse away a hot afternoon
打着瞌睡度过炎热的下午
Slumber
Slumber作为一种文学表达，有安稳好眠的意思。
Slumber: (literary) sleep; a time when someone is asleep
She fell into a deep and peaceful slumber.
她睡着了，睡得又沉又香。
Repose
Repose 指躺着休息、静卧，也可表示长眠、安息。
Repose: (literary) a state of rest, sleep or feeling calm
The delightful sofa invites repose.
这舒适的沙发让人想躺下休息。
I prayed for the repose of his soul.
我祈祷愿他安息。
Lethargy
/ˈleθədʒi/
Lethargy有无精打采、死气沉沉的意思，也可以表示昏睡、嗜眠，与之相对的是则是失眠 (insomnia)。
Lethargy: the state of not having any energy or enthusiasm for doing things
He felt that he had to drag himself out of his lethargy and begin to write.
他觉得自己必须从昏沉中振作起来，开始写作。
