1
be a [adjective] sleeper
常用 light、heavy、sound 等形容词修饰 sleeper，说明睡眠的深浅。
He is a heavy sleeper and rarely wakes up at night.
他是一个睡得很沉的人，夜里很少醒。
睡眠者；睡着的人
先理解核心含义，再看它在真实句子里的用法。
睡眠者；睡着的人
a person who is sleeping
He is a heavy sleeper and rarely wakes up at night.
他是一个睡得很沉的人，夜里很少醒。
睡觉的人。
Someone who sleeps.
地板中与下方搁栅和上方地板均垂直的结构梁。
A structural beam in a floor running perpendicular to both the joists beneath and floorboards above.
正在睡觉的人
a rester who is sleeping
处于休眠状态的事物(如法律)。
That which lies dormant, as a law.
The baby is a heavy sleeper, so the fireworks did not wake her.
这个婴儿睡得沉，所以烟花声没有吵醒她。
AI contextual example
She is such a light sleeper that a dripping tap can disturb her.
她睡觉很轻，连滴水的水龙头声都能打扰她。
AI contextual example
The inn has a quiet wing for sleepers who want an early night.
这家旅馆为想早睡的旅客设了一个安静的区域。
AI contextual example
the winner was a true sleeper--no one expected him to get it
获胜者是一匹真正的黑马——没人预料到他会赢。
WordNet
常用 light、heavy、sound 等形容词修饰 sleeper，说明睡眠的深浅。
He is a heavy sleeper and rarely wakes up at night.
他是一个睡得很沉的人，夜里很少醒。
sleeper 表示“睡觉的人”时是可数名词，可用 there be 句型表达某处有若干人在睡觉。
There were three sleepers in the room.
房间里有三个睡着的人。
sleeper 也可指火车上的卧铺，book a sleeper 是常用搭配，后接 on + 车次或路线。
We booked a sleeper on the overnight train to Edinburgh.
我们在去爱丁堡的夜班火车上订了一个卧铺。
sleeper 还指铁路枕木，常用复数 sleepers，后可接 under the tracks/rails 说明位置。
The concrete sleepers under the tracks have a longer service life.
轨道下面的混凝土枕木使用寿命更长。
Not this
She is a sleeper.
Use this
She is sleeping.
sleeper 是名词，意为“睡眠者”，指身份或习惯，不能表示当前正在进行的动作；描述某人此刻正在睡觉，应用现在分词 sleeping（构成现在进行时）。
Not this
I need a sleeper.
Use this
I need some sleep.
sleeper 指“睡眠者”或“卧铺”，不能表示“睡眠”这一抽象概念；表示需要睡觉时，应用不可数名词 sleep，如 some sleep。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
睡眠浅的人
My roommate is a light sleeper, so I walk quietly when I come in.
我的室友睡眠很浅，所以我进来时都轻轻地走。
睡得沉的人
He's a heavy sleeper and can sleep through a fire alarm.
他睡觉很沉，连火警警报都吵不醒。
卧铺列车
We took the sleeper train from Paris to Madrid.
我们乘坐从巴黎到马德里的卧铺列车。
铁路枕木
They had to replace several railway sleepers after the storm.
暴风雨过后，他们不得不更换几根铁路枕木。
卧铺铺位
A sleeper berth costs extra on this route.
这条线路上的卧铺铺位需要额外付费。
黑马作品；出人意料获得成功的作品
The indie film became a sleeper hit, earning millions at the box office.
那部独立电影成为黑马，票房收入数百万。
潜伏特工；卧底间谍
The spy had been a sleeper agent for years before being activated.
这名间谍在被激活前已潜伏多年。
潜伏小组；敌后小组
Police arrested a sleeper cell planning an attack.
警方逮捕了一个正在策划袭击的潜伏小组。
科幻电影《沙丘》中的经典台词，意为“沉睡者已醒来”。
She took the overnight sleeper to Glasgow.
她乘坐夜间卧铺列车去格拉斯哥。
发长 /iː/ 音 (如 see, free)
Use sleeper naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
联想：sleep（睡）加 -er（表人），sleeper 就是“睡眠者”；再想火车卧铺上的睡眠者躺在枕木上，sleeper 也指枕木/卧铺。
语域：neutral 常见场景：日常对话、睡眠习惯描述 表示“睡觉的人”时，sleeper 为中性词，通常用于日常对话或描述睡眠习惯，如 light sleeper（浅眠者）、heavy sleeper（沉睡者）。正式场合也可使用，但无特殊文体色彩。
keeper, deeper, sweeper and cheaper rhyme with sleeper because they all end in /ipɚ/; note cheaper is spelled -eaper. Be careful: sleep and steep look similar (spelled -eep) but are pronounced /slip/ and /stip/ without the final /ɚ/, so they do not rhyme with sleeper.
Dictionary facts from ECDICT, WIKTIONARY.