I was hoping ~
When stated after the event has occurred/not occured, it implies something (slightly) expected and pleasent came true/ the opposite came true. The expectation doesn't have to be something you were 100% certain of, it could be more like 60% (I think it is possible, but I dont know for sure). Tone of voice and emphasis will tell you which way:
I was hoping he'd pick me... (he picked another person)
I was hoping you'd buy a large pizza... (they bought a small or medium)
A dissapointed voice means that the hope didnt happen. If any words are emphasized, they are the relevant part of the wish.
I was hoping you say that!
I was hoping he'd be here.
If the tone is happy, it means the wish came true.
Note that in the above, the statement was made after the event happened or the opposite happened. If stated before the event, then the speaker is expressing their desires. It can sometimes also be a request, but it feels a little demanding.
I was hoping you would take a look at my computer
A more polite version of all three of these is the "could" version.
Because "could" is a form of "can", it feels like the situation is responsible, not the people.
I was hoping he could make it to the party... (but he did not make it, maybe he was busy with work)
Just as before, the speaker is expressing dissapointment, but is explicitly not blaming anyone.
I was hoping you could eat with us (as they are all at dinner together)
This expresses joy, but makes it seem like they were doing you a favour. It's an indirect way to say thank you.
I was hoping you could help me with my homework
This is a polite request.
Anyways, for the non-requests versions, you can change the tense from simple present to present perfect (notice -> have noticed) and it means basically the same thing. But it adds the nuance that the wish coming true or not has some significance to the present.
I was hoping you would have been home (but since you are not, you will miss Game of Thrones)
I was hoping you'd have known the answer (and because you did, you were able to tell the answer to me, yay!)
The sentence as it stands there is not correct.
This is due to the circumstance that to sleep is usually an intransitive verb that does not take an object. With the leading was the construction would be passive voice, but English doesn't use intransitive verbs that way. However, intransitive verbs can use the past continuous and thereby was sleeping.
sleep intransitive verb
to rest in a state of sleep - MW
Admittedly there are transitive uses of sleep, but they do not fit in the construction of the sentence in the question.
The problem with intransitive verbs is that they don't go over into a passive voice. I.e. you can't be slept. If it was a transitive verb that took an object that would easily be understood. Take the transitive verb to slap for example.
I was slapped when he came back to the home.
This sentence offers two explanations at once. Firstly it's homophone to the sentence from the original question. Thus, it might be what was spoken if the question is based on something heard.
Secondly it shows that two past tense verbs can actually be just simple past but in a passive construction.
In the most commonly considered type of passive clause, a form of the verb be (or sometimes get) is used as an auxiliary together with the past participle of a transitive verb; - Wiki: Passive Voice
A transitive verb is a verb that requires one or more objects. This contrasts with intransitive verbs, which do not have objects. Transitivity is traditionally thought of as a global property of a clause, by which activity is transferred from an agent to a patient. - Wiki: Transitive verbs
Best Answer
Both are acceptable: the reason at the time was x and it still is X, and will be in the future.
So which you use depends on the context.
If you’re explaining to your boss why you arrived late an hour ago, you would use is:
If at lunch you’re telling a friend what you said to your boss, you would use was:
But if some weeks later you’re telling somebody why you got fired, you’d have to change the time reference:
And by the way, you might not have been fired if you hadn’t said you slept in—that implies, at least in US usage, that you did it on purpose. Next time tell your new boss I overslept, and maybe he’ll be more forgiving!