The second sentence is said by using had. This sounds like past perfect tense. What is the difference if I don't use had?

I slept less often when I was in Canada.

I had slept less often when I was in Canada.

  • The first one talks about you sleeping less in general whereas in the second sentence, it talks about a specific time/ocassion when you slept less in Canada.
    – Maulik V
    Jun 2, 2014 at 10:59

3 Answers 3


"I slept less often when I was in Canada" just states the fact about how often the speaker slept while in Canada.

"I had slept less often when I was in Canada" states the same fact but also suggests that after leaving Canada, the speaker slept more often than when in Canada.


Here's why: the perfect tense means that an action is complete at the time being described.

There are many reasons why you might want to suggest that an action is complete, there are many things that "completion" might mean, and the most relevant action completed might not even be named by the verb. The specifics are provided by context, which can greatly change the meaning of the perfect tense.

One common reason to use a perfect tense is to contrast with what came after the action was completed. This reason leads to the interpretation above: "my period of sleeping-less-often was completed while I was in Canada; it did not continue afterward."

Another common reason is to indicate that the completed state of a process produced some relevant effect at the time being described:

After years of grogginess whenever venturing north of the 49th parallel, my experiments with the Mounties' amphetamines finally succeeded. I had slept less often while in Canada. Indeed, I have slept less often ever since.

This time, the second sentence means "my period of trying-to-sleep-less-often-while-in-Canada successfully completed" or really, "I slept less often because I was under the influence of the amphetamine experiments which had successfully completed at that time." In the third sentence, the present perfect means that the completed action (the experimentation or the attempts at sleeping less often, take your pick) continued to exert its effect after the speaker's time in Canada, continuing to the present day.


The perfect aspect is often used in sentences taking place over a span of time. For this reason, it's important to analyse its use in context. The second sentence, as it stands,

I had slept less often when I was in Canada.

is begging for more context, for example:

I told my English GP that I had slept less often when I was in Canada.

Now, the time span is clearer and the sentence sounds neater.

Let's consider now the first sentence and the second sentence with the extended context:

I slept less often when I was in Canada.

I told my English GP that I had slept less often when I was in Canada.

The difference due to using the perfect aspect is that, although both sentences imply that your sleeping patterns have now returned to normality, the latter sentence highlights the span of time when this took place.

Please, refer to this canonical post for a more thorough description.

  • I don't see why you say OP's sentence "sounds off" without context. It's perfectly (sorry! :) ordinary English, and the fact of it being past perfect simply tells us that if we did have the context, we can be quite certain it would already be in the past tense. (Unless we knew it didn't come from a native speaker.) Jun 2, 2014 at 16:38
  • @FumbleFingers it doesn't sound off when one can infer the context (as you did in your answer). I'm going to rephrase my answer, based on your comment.
    – Nico
    Jun 2, 2014 at 16:53
  • Sorry, I still don't understand. If you come across a sentence like "I slept less often" with no other context, you wouldn't say that's somehow "odd" compared to "I sleep less often" - they're just normal sentences which in and of themselves imply different temporal contexts, regardless whether you can actually see that context or not. The same point applies to "I had slept less often", or indeed "I will sleep less often". Jun 2, 2014 at 17:01
  • @FumbleFingers Of those 4 examples, I still think that "I had slept less often" needs more context. On its own, that sentence doesn't have a reason to be. On the other hand, the other 3 examples don't need additional context to understand their meaning. If I get your answer right, you're arguing that some speakers do not distinguish "simple past" from "past perfect". In my answer, I just wanted to explain the standard use of the past perfect in the OP's examples.
    – Nico
    Jun 2, 2014 at 17:09
  • The bit about not always bothering with past perfect is really a separate issue. The substantive point is that all the tenses I used in my preceding comment here are quite ordinary, and inherently define the temporal context in which they would be used. So none of them are inherently more or less "normal" - they're just tenses, plain and simple. Jun 2, 2014 at 17:13

I think this should all be covered by Canonical Post #2: What is the perfect, and how should I use it?, but that's a pretty long answer. The relevant bit for OP here is...

Use perfect constructions to introduce prior eventualities as context for the current discussion.

What that actually means is if you're currently discussing something in the present, and you want to refer to something that happened earlier, you use simple past. But if you're discussing something that's already in the past, you might use past perfect to refer to something even earlier. To illustrate...

1: "I don't know why I am so tired all the time. I slept less often when I was in Canada, and I wasn't tired then."

2: "I didn't know why I was so tired all the time. I had slept less often when I was in Canada, and I wasn't tired then."

Note that many pedants would say it should be ...I hadn't been tired then in #2, but in practice many if not most native speakers wouldn't bother with that (personally, I wouldn't necessarily bother with past perfect for the preceding had slept either, since the fact that you're talking about a time even further in the past is obvious anyway.

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