When did you wake up?

I woke up at 10.

But then if I say, “When did you sleep?”

I slept at 10. – seems difficult to digest!

That's because sleep is a process that includes duration.

I slept for 10 hours. – this way, it's digestible!

But when I mention the point of time, is it okay?

Strange thing is, if I'm describing my habit/routine, it's perfectly fine..

I sleep at/by 10

I request not to take this question 'logically'. It's about English. Nobody is perfect in timing. Please don't argue that you cannot have 'perfect time' of sleeping because you don't know when you slept. I'm talking about the sentence structure and not precise timings.

By the way, “I slept at 10” is very common in India.

  • 9
    "Sleep" is a long process. It never spans just one minute. "I was sleeping at 10 o'clock" means "I was in the process of sleeping as 10 o'clock went by". That's perfectly fine. I've never heard "I slept at 10" and so it doesn't seem right to me. In fact, if I didn't know better, I'd suggest you had made a mistake and wanted to say "I fell asleep at 10 o'clock".
    – JMB
    Commented Mar 20, 2015 at 6:49
  • 6
    Does I slept at ten indeed mean the same as I went to sleep at ten? Somehow I have no problem with the sentence, it feels all right (and that's not because of my mother tongue, because in Dutch it does not sound OK).
    – oerkelens
    Commented Mar 20, 2015 at 10:32
  • 3
    This ELU question is interesting.
    – oerkelens
    Commented Mar 20, 2015 at 12:47
  • 1
    There's also the problem of knowing exactly when one begins to sleep. That is, I may go to bed at 10, but will not enter a sleep state until some time after that - and if I look at a clock to see what time it is, that means I'm still awake :-)
    – jamesqf
    Commented Mar 20, 2015 at 17:58
  • 2
    @MaulikV: what you say doesn't follow, because the opposite of "wake up" or "awaken" isn't normally "sleep", it's "go to sleep" or "fall asleep" (or I suppose "start sleeping" although that's not a natural phrase). The opposite of "sleep" isn't "wake up", it's "be awake". They just aren't symmetrical as you'd expect. Like the answer over on that other question says, you can sometimes use "slept" to mean "went to sleep" in British or American English, but it's out of the ordinary. As you can see, it provokes argument between native speakers whether it's correct or incorrect :-) Commented Mar 20, 2015 at 23:51

9 Answers 9


No, we would not say "I slept at 10". (AmE). Either say

  • I was sleeping at 10. (this means you were also sleeping some before and after 10) or

  • I {fell asleep/went to sleep} at 10. (means you were not sleeping before 10.)

  • 5
    @Eric I can't accept your use of Google NGram. The phrase "slept at" can be used in multiple contexts (e.g., "I slept at work"), but if you force it to be in the context of time, the story is reversed. (But the data is sparse, I wouldn't appeal to Google here.) Commented Mar 20, 2015 at 17:15
  • 2
    I would, and in the past have, said things like, "I slept at like 3:00 AM last night, I'm so tired," etc. I disagree that "I slept at ___" is incorrect or uncommon.
    – HC_
    Commented Mar 20, 2015 at 19:26
  • 2
    @HC_ If you said "I slept at like 3:00 AM last night" I would need to ask for clarification on whether you started sleeping then, or if you're trying to say that were asleep at that time. It might not be 'incorrect' but it's uncommon and ambiguous.
    – DCShannon
    Commented Mar 20, 2015 at 21:17
  • 6
    I agree with @DCShannon. It may not be consistent with things such as "I ate at 10," but English is not always consistent. I can't remember hearing anyone use the expression "I slept at <time>," and I wouldn't recommend someone learning English to pick it up. To make it clear, say "I went to sleep at 10," which is the usage I always hear and use, and removes ambiguity.
    – Alex
    Commented Mar 21, 2015 at 3:24
  • 3
    Anyone relying on pure logic to interpret English is going about it all wrong. Yes, eating isn't a momentary action (although it's a much shorter timeframe than sleep, which is supposed to be a third of a day), but in fact if you say "I slept at ten" people are likely to be somewhat confused, while if you say "I ate at ten" people will not be confused.
    – cpast
    Commented Mar 21, 2015 at 4:31

You can't use 'wake' and 'sleep' in the same way because they have significantly different meanings.

'Wake' is specifically a transition from one state to another. When I wake, I stop sleeping and start being awake. This happens at a moment in time, so I can specify just one moment. "I woke at 10."

'Sleep' is an ongoing process. I start sleeping, sleep for a while, and then end. My sleeping didn't occur at any one point in time, so I can't say when it happened. I can however say when I started sleeping. "I fell asleep at 10."

This is why "I slept at 10" is ambiguous and confusing. I don't know what point in the sleeping process you're referring to. It sounds like you're just saying you were asleep at 10.

Common forms for this expression include

  • "I fell asleep at 10"
  • "I went to sleep at 10"
  • "I went to bed at 10"

However, note that "going to bed" does not necessarily imply "going to sleep". I may go to bed at a point in time, engage in other activities such as reading, and then fall asleep at a later point in time.

If you wanted to say when you normally go to sleep, rather than when you went to sleep one particular time, then common phrases include:

  • "I go to sleep at 10"
  • "I'm asleep by 10"
  • "My bedtime is at 10"

The most precise phrasing is the first. The second implies that you may sometimes fall asleep earlier than 10, and the third only refers to going to bed, which may or may not be when you go to sleep.

Sometimes other short activities - short meaning about an hour or less - can be referred to as if they took place at one particular moment, such as eating. It would be more common to say "I ate at 10" than "I started eating at 10", unless you were having a very long meal. If I take a short nap, I might even say "I napped at 10".

Note on Definitions

Note that 'slept' is the simple past tense and past participle of 'sleep'. After checking Wiktionary, Merriam-Webster, and the Oxford Dictionaries, none of them have "start sleeping" as a listed meaning for 'sleep'.

On the other hand, 'woke' is the simple past tense and past participle of 'wake'. In all three sources, the definition for 'wake' means to "stop sleeping", as in this definition from Merriam-Webster:

to stop sleeping : to become awake after sleeping

  • 1
    This is definitely the most complete answer, but to make it the definitive answer, I think you should mention the apparent inconsistency of rejecting "I slept at 10" while accepting "I ate at 10". If I was an ELL, that might make me wonder if there was some obscure grammar rule that I missed somehow. Commented Mar 21, 2015 at 2:21
  • 2
    @DoctorDestructo: I don't think the answer is lacking anything. The contrast between "sleep" and "wake" is clear, and if one asks why "eat" acts like "wake", it shouldn't take them very long to figure out that "eat", like "wake", is a short-term action, not one of extended and indefinite duration like "sleep"
    – Ben Voigt
    Commented Mar 22, 2015 at 3:07
  • @Ben Voigt A meal also has an "extended and indefinite duration", but its start time is usually known and even scheduled in advance, which makes it a very common topic of conversation. By contrast, you almost never know the specific time at which sleep begins. Except in a few specific contexts, any statement that provides a start time for the act of sleeping will sound awkward. It's the subject matter that makes it so, not the grammar. It really doesn't matter how you say it. The statement "I fell asleep at 10" is just as likely to be questioned as "I slept at 10", if not more so. Commented Mar 23, 2015 at 13:03
  • @Ben Voigt The fact that you compared eating to waking up instead of falling asleep (which would have been more relevant in the present context) demonstrates that it's not about duration, but rather, what can and can't be known. People usually know what time it is when they wake up. Looking at a clock is often the first thing they do. That's why statements like "I woke up at 8" are common, while statements like "I fell asleep at 10" aren't, even though they're really two sides of the same coin. Commented Mar 23, 2015 at 14:13
  • @DoctorDestructo: The action of "eating" definitely is not instantaneous, but neither is it extended (in Western cultures, anyway)
    – Ben Voigt
    Commented Mar 23, 2015 at 16:32

As Brian has already said: "I was sleeping at 10" and "I fell asleep at 10" are correct.

However, I just want to add that, if you necessarily want to use "slept", "I slept from 10 (o'clock)" is correct too. This is usually followed by "to", for example: "I slept from 10 PM to 6 AM".

  • 12
    I’ve never heard “I slept from 10” without “to” and an end-time (AmE). Commented Mar 20, 2015 at 14:28

Here's what's going on: the primary meanings of the words "sleep" and "at" are slightly incompatible, but combining them leads some people to stretch them beyond their primary meanings in a reasonable way, and some people refuse to stretch them.


The primary sense of the word "at" is spatial: it mainly indicates a location without regard to its structure. You say "I am at work" or "I work at 10th St. and Main" when you just mean the location; you say "I am in the building" when you want to distinguish being inside or outside. My answer here gives more details. The main thing to notice is that "at" tends to suggest that you are regarding a location as a point in space even if really it's larger than that.

When you use "at" temporally, you're making an analogy with its spatial sense, so "at" tends to indicate a point in time. So, you say "My plane landed at 1:34" or "We're going to have a meeting at 9:00."

Stretching slept and at to make sense with each other

Sleeping usually takes a long time. It doesn't happen in an instant. But "at" suggests that you are talking about an instant. Strictly speaking, that's a contradiction. So, when you say "I slept at 10:00", a listener must stretch "sleep" and/or "at" in some way to make sense of the sentence.

Before I explain what happens, let's look at "We had a meeting at 9:00." A meeting, just like sleeping, also takes time. It doesn't happen in an instant. But no one is stupid or dogmatic enough to insist that you always say "a meeting from 9:00 until 10:00" or "a meeting starting at 9:00". No one interprets "a meeting at 9:00" to mean "a meeting that lasts only an instant, occurring at 9:00". People reasonably interpret "a meeting at 9:00" to mean "a meeting that starts at 9:00". Since "at" suggests a point in time, and a meeting extends for a range of time, you have to think of what would some reasonably mean by "a meeting at 9:00". Since usually you want to indicate when a meeting starts, so you can all arrive at the same time, you reasonably take "We had a meeting at 9:00" to mean "We had a meeting that started at 9:00".

When someone hears "I slept at 10:00", they are in the same position as when they hear "We had a meeting at 9:00", with two differences. (1) Using "at" with "sleep" is unfamiliar, so it might be a new stretch for them. (2) The verb "meet" does suggest an instant in time: the instant when you meet. It's hard to know exactly when you fall asleep, so the idea of a starting time for sleeping is not as salient. Whenever people talk about scheduling meetings, the start time becomes salient—that is, your mind is primed to easily put attention on the start time. Since we don't usually talk about the start time of sleep, it doesn't "jump out" as easily as the obvious meaning that you have in mind. A listener wonders if maybe you misspoke or if they misunderstood.

Dictionary-thumpers refuse

Some people are less willing than others to bend words beyond their usual limits. You've probably encountered a few people who, when you bend a word to communicate your meaning when no other word has a closer meaning, opens up a dictionary, points to the definition, says "You're wrong!", and proceeds to disprove, with ironclad logic, the absurd proposition that results when the dictionary definition is taken as what you meant.

That's crazy, and happily not very common, but the fact is, there is a wide range in people's willingness to reasonably stretch words beyond their primary meanings or the usual things they're accustomed to hearing them applied to. Some people go along with the reasonable stretch easily; some refuse to go along with it until it becomes familiar through other people's usage.

Describing a routine

So why is it less objectionable to say "I sleep at 10:00" when describing a daily routine?

I think there are two main factors here: when describing a routine, you usually treat each activity without regard to its structure, often mentioning only its start time; and a routine is a plan, not an actual event.

Wake up at 6:00 a.m., jog at 6:30, breakfast at 7:30, start work at 8:00, status meeting at 9:00, lunch at 12:00 p.m., resume work at 1:00, leave work at 5:00, dinner at 6:00, post to ELL at 7:00, and sleep at 10:00.

The succession of "at"s establishes that each time is the start time for an activity. "At" is appropriate because the schedule doesn't describe what happens inside each activity. So, a reader is less likely to notice that "sleep at" would be unusual in other contexts. Proximity agreement is another situation where people often don't notice that a norm has been violated, because some other, more-salient factor drowns it out.

But probably the more important factor here is that a routine is a plan, not an actual series of events. A plan is an idealization, which exists only in your mind. So, in your mind, as you plan out your routine, you imagine that you start sleeping at precisely 10:00, just as your meeting starts at precisely 9:00. In an idealization, you think of activities as starting at precise, known points in time even though you know they won't go exactly like that in reality. That makes "at" a very good fit. But if you say "Last night, I slept at 10:00", this sounds strange because it suggests that you know precisely when you fell asleep, and in reality, that doesn't happen.

The grammatical principle

The grammatical principle here is that grammatical rules can't explain what's going on with an unusual use of a preposition as in "I slept at 10:00". Meaningfulness and grammaticality result from a hazy interaction between many factors:

  • the primary meanings of the words

  • the clash that results when they're combined

  • the reasonableness or distance of the stretch from the words' primary meanings

  • the salience of elements of the topic that make good, nearby targets for stretching the words

  • the familiarity of the word combination or the manner of stretch

  • the listener's ability and willingness to go along with the stretch

and one more thing, which I haven't mentioned yet:

  • competition from other words.

When there is already another, familiar way to indicate the same meaning, people are usually less willing to go along with a stretch. Instead of "I slept at 10:00", you would ordinarily say "I fell asleep by 10:00" or "I went to bed at 10:00" because of that uncertainty about when you actually begin to sleep. Since there is another way to say what a listener thinks you probably mean, this is evidence that either you misspoke or the listener misunderstood—which is reason for a listener to be less willing to stretch "slept" to mean "started sleeping". To stretch a word beyond its usual limits, people usually want some need to be satisfied by that stretch: some aspect of communication to be served, which is not already well served by a familiar construction.

  • I loved your answer! +1 But do you agree that if I use 'I slept at 10 last night' (irrespective of the timing), it's grammatically okay?
    – Maulik V
    Commented Mar 21, 2015 at 11:09
  • 1
    @MaulikV Well…it's grammatically OK subject to the factors described above. It's at the hazy boundary of grammaticality. In the U.S., most people will find it jarring because it gives them doubts about how you intend to hook up the words to produce a meaning (which is what I understand by "grammatical"); most of the other answers talk about that. Some people will go along with it and some won't. That could easily change if "slept at time" becomes common and familiar. But such a change would have to overcome the resistance described above.
    – Ben Kovitz
    Commented Mar 21, 2015 at 11:21
  • In case you're wondering why this isn't getting more upvotes, let me explain why I'm not upvoting: This answer makes some excellent points regarding listeners' willingness and ability to guess what a speaker means when they use an unusual phrasing, but the question was about usage, and the usage examples seem wrong to my ears. In particular, there are many references to the phrasing "went to sleep at [time]" as if it were 'wrong' or unusual to use 'at', and also a suggestion that "I sleep at [time]" is not 'wrong' or unusual.
    – DCShannon
    Commented Mar 24, 2015 at 0:29
  • @DCShannon Thanks for the thoughtful suggestions. I'll see if I can clarify. I probably got the wordiness/clarity trade-off wrong in some places. Regarding "went to sleep at [time]", can you point me to a specific place where I made it appear to be 'wrong' usage? Regarding "I sleep at [time]", do you mean the part in "Describing a routine"? It says there "less objectionable", not "unobjectionable", but maybe that's too subtle. I'm trying to say that "I sleep at [time]" asks listeners to accept a greater stretch from customary usage than many are willing to accept, and explain why that is.
    – Ben Kovitz
    Commented Mar 28, 2015 at 22:17
  • I looked back over it, and I think I'm probably reading statements that you intend to apply to a hypothetical listener who objects, but which sound like they apply in the universal. "So why is it less objectionable to say "I sleep at 10:00" when describing a daily routine?" Makes it sound like it is your opinion that it sounds less objectionable, as opposed to "Why might "I sleep at 10:00" sound less objectionable to some listeners?"
    – DCShannon
    Commented Mar 31, 2015 at 3:57

To sleep is usually understood to mean to be in the state of being asleep, not to fall asleep. Because sleeping is usually a long event (eight hours is commonly quoted), stating that you were asleep at a particular hour or a specific time makes little sense, unless you also state that you only slept for a short amount of time.

to sleep: to be in the state of being asleep

to fall asleep, to go to sleep: to change state from being awake to being asleep

to wake, to awaken: to change state from being asleep to being awake

to be awake: to be in the state of being awake

                awake             asleep
be in state     to be awake       to sleep
change state    to (a)wake(n)     to fall asleep

So sleep is not the opposite of wake. Asleep can be either an adjective or an adverb, sleep can be either a noun or a verb. I'm not aware of any single word verb for to fall asleep e.g: to go to sleep, to pass out, to lose consciousness, to become unconscious, etc. Here sleep and wake are used as verbs, while asleep and awake are used as adverbs with another verb to make it grammatically correct. Note the lack of symmetry!

When did you fall asleep? I fell asleep at 10 pm.

How long did you sleep (for)? I slept for eight hours.

When did you sleep? I slept from 10 pm till 6 am.

When did you sleep? I slept last night. (A long enough period of time to complete the process)

When did you sleep? I slept at 10, 11, 1 & 4 but I was awake the rest of the time.

In the sentence I ate at 10, eating usually takes less than an hour, so it is not saying that you were eating for exactly one minute at 10 o'clock but that you started eating at some time close to 10 and continued until you were finished a short time later, whether that took you five minutes or half an hour. Both I ate at 10 and I slept at 10 imply that you weren't doing the same activity at 9 o'clock or 11 o'clock.

Please note that Indian English uses words and meanings considered non-standard in other varieties of English such as prepone as an extension of postpone. It seems that these words and meanings crop up because Indians assume a symmetry in English that does not usually exist. They can be usually be understood without further explanation but cause initial surprise when encountered. Since you said that I slept at 10 is common in India, keep using it when speaking to Indians. Just be aware that not everyone outside of India will understand that you mean I fell asleep at 10. So most people will understand you even if they would not say it that way themselves.

It is to do with the amount of time it is expected for the activity to finish.

I drove to work at 8. I arrived at 8:30. I worked at 9. I slept at 10 but luckily I woke at 10:30 before the boss saw me at 11. I ate at 12.

drove - continuous, less than an hour is common

arrived - a single moment

worked - continuous, less than an hour is uncommon, up to eight hours is common, sometimes (a lot) more

slept - continuous, less than an hour is uncommon, eight hours is considered normal

woke - a single moment

saw - may be either a single moment or continuous depending on context

ate - continuous, less than an hour is common

Note that my story is very fragmented, and not just because it is using very short, simple sentences. It's not clear what I was doing between 8:30 and 10 except at 9 or between 10:30 and 12 except at 11 because I only said what I was doing at specific times. It is assumed that I was driving for half an hour and that I slept for half an hour because they are both continuous activities and the next event in the story concludes each of them.


I slept at 10.

This is grammatically correct, however, it sounds strange to my ears. But I don't think anyone would be confused hearing it in a conversation and would know what you were saying. If you are looking for an alternative, I would say something like:

I went to bed at 10.

  • I believe Maulik intends the sense you detected and wishes to indicate a start-time, not an end-time. He’s using “slept” to say “went to sleep”. Commented Mar 20, 2015 at 14:35
  • @TylerJamesYoung Ah, thanks for the clarification. Commented Mar 20, 2015 at 14:43
  • -1, I would be confused hearing that in a conversation. Also, going to bed at 10 and falling asleep at 10 are not the same thing. I might go to bed at 10, read for an hour, and fall asleep at 11.
    – DCShannon
    Commented Mar 20, 2015 at 21:19
  • 1
    Hang on, you answered saying "nobody would be confused, they'd understand it to mean X", and then when told it actually meant Y, switched to "nobody would be confused, they'd understand it to mean Y". I think this demonstrates that at least some people would be confused :-) Of course the context of the conversation might sort it out, or you could continue the conversation by asking what it meant, but it all points to the phrase itself being unclear. Commented Mar 20, 2015 at 23:45
  • I have to agree with user3738893; most English speakers won't be confused. People have a natural tendency to choose the "least odd" interpretation of any given sentence, even if it differs significantly from the literal interpretation. In most contexts, the least odd interpretation of "I slept at 10" would be "I went to bed at 10". Commented Mar 21, 2015 at 15:50

I'm not sure what you're trying to convey. If you'd like a sentence with the same meaning as "I woke up at 10", you can say:

I slept until 10.

If you are trying to say that you began sleeping at 10, you could use either:

I went to sleep at 10.

I went to bed at 10.

If you are trying to say that at 10, you were asleep (not awake), you could use either:

I was sleeping at 10.

I was asleep at 10.

  • @dcahannon it seems like you're trying to imply that "I stopped being asleep at 10" means something other than "I woke up at 10" Commented Mar 22, 2015 at 4:07
  • I'm not 100% sure what I was looking at earlier. Maybe it looked like all those phrases were supposed to mean the same thing. Your response makes even less sense than my original comment. I would rescind the downvote if an edit were made.
    – DCShannon
    Commented May 29, 2015 at 21:06

It's not incorrect grammatically, it's more of a logical issue. The amount of time you spend sleeping is usually arbitrary, unlike say eating or getting a haircut.

I ate at four. Sounds right because it conveys when you starting eating and one can reasonably estimate when you stopped eating.

I drove ate four. Only sounds right if you have some understanding of wear they were went. If you say just say "I drove at four", it sounds weird.

I baked at three, Sounds off unless you know what was baked.

I showered at three. Sounds right, because you can estimate how long it took.


The phrase "I woke up" refers to the point at which you began being awake, while the phrase "I slept" refers to the state of being asleep, but not specifically to its beginning. As others have already mentioned, you would say "I fell asleep" or "I went to sleep" to refer to the point at which you began sleeping.

But that's all really beside the point. The real problem with the statement "I slept at 10" is not the fact that it doesn't target the beginning of the act of sleeping. And, contrary to what you may read in some of the other posts and comments, it has nothing to do with the duration of a typical night's sleep relative to that of other activities. The real problem is, sleeping is not a process that typically has, or can have, a known start time.

Consider the following statements:

  • "I ate at 11"
  • "I work at 8"
  • "My show is on at 7"

Almost all English speakers would be perfectly comfortable with those statements even though they refer to processes that vary widely in duration, and none of them explicitly target the beginning of a process. They are accepted because they all deal with processes that tend to have easily identified start times. That's the general rule you need to follow. If you find yourself associating a start time with a process that normally doesn't have a known start time, then you probably need to stop and think about what process you're really talking about. In this particular case, if you replace "slept" with "was in bed", I don't think anyone will find your statement the least bit odd. That's because it's very common for a person to know what time they start being in bed each night.

  • This answer makes it clearer than the others that the difference is related to the difference between an ongoing process and the start of that process. However, I don't think the explanation in the second paragraph makes sense. "I ate at 10" sounds better because eating doesn't take 8 hours. You can both start and finish at about 10.
    – DCShannon
    Commented Mar 20, 2015 at 21:15
  • 1
    When most people hear the phrase "I ate at 10", I don't think they assume it was a quick meal. I think they assume the speaker was referring only to the time at which the meal began, whether it was a quick bite or 4 hour banquet. That's because it's a very common thing to talk about. People tend to know what time it is when they start a meal. They often do it on schedule. But it's almost impossible to schedule, or even be aware of, the specific time at which you start sleeping. In fact, it's such an unusual thing to talk about that I think it would sound strange no matter how you said it. Commented Mar 20, 2015 at 23:35
  • 1
    Given the examples after your edit, I actually think "I work at 8" sounds odd, specifically because working is a long process, whereas shows come 'on' at a specific point in time (i.e that statement explicitly targets "the beginning of a process"), and eating is a very short activity. I would expect "I go to work at 8" or "I start work at 8".
    – DCShannon
    Commented May 29, 2015 at 21:08
  • @DCShannon The statement "I work at 8" might seem more familiar to you if you put it in the context of a sentence, such as "I can't stay out late because I work at 8 tomorrow", or "I work at 8, so I'm usually up by 7:30". Re. your other two points: 1) it makes little sense to call eating a "very short activity" since its duration varies, and there is no general rule by which we can make such judgements; 2) the statement "my show is on at 7" does not explicitly refer to the beginning of a process, any more than the other two examples I gave. Commented Jun 1, 2015 at 16:19
  • I would probably not say "I work at 8, so I'm usually up by 7:30." I usually say "I start work at 8" or "I have to work at 8" so I agree with @DCShannon that it sounds odd. Maybe because sleeping and working are longer durations than eating or say, showering, but maybe it's because sleeping and working are more of a state than an activity.
    – ColleenV
    Commented Jul 7, 2015 at 20:14

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