was sleeping / had been sleeping

[Verona_82]

Hello,

I'd appreciate it if somebody could have a look at my thoughts and comment on them. I need to explain the difference between the following sentences:

(1) I was sleeping until you came
(2) I had been sleeping until you came

I think (2) implies a longer process.Perhaps I woke up because you came.
(1) only says I was asleep at some time before your arrival.

Would adding "for 2 hours" make (1) sound fine too?

Thank you!

[5jj]

Frankly, I don't feel any real difference between the two.

I do feel that 'asleep' is more natural than 'sleeping' in both.