Learn English – What dialect is “I be doing this”

I don't live in America, but I don't usually say, "I fell asleep..."

Where I live, there seems to be a distinction.

"I slept at 10 o'clock" where I live seems to mean that we got into bed at ten o'clock.

However, we would then specify, "but I didn't fall asleep until eleven o'clock."

To my ears, there is nothing ungrammatical.

And, answering your other statement:

"I couldn't sleep until midnight", which sounds right to me, although "I didn't sleep until midnight" sounds wrong.)

There is a slight difference in meaning to me: I couldn't sleep until midnight indicates an inability to sleep, whether or not you waanted to.

"I didn't sleep until midnight" could mean that you were unable to fall asleep as well, but it has an additional meaning of perhaps you just didn't, that is, you maybe sat up late reading a book, and so didn't sleep until midnight.

From the eggcorn database:

Like wrought » rot and naught » not, this is an eggcorn that works best for those with the cot/caught merger.

Hawk ‘to offer for sale (by calling out in the street)’ and hock ‘to pawn’, though not etymologically related, are semantically close enough to make this a relatively common eggcorn.

Note also that hawk in the sense of ‘cough up phlegm’ (as in hawk a loogie) often appears in the form of hock (see David Wilton’s Wordorigins).

So, you're right to be suspicious. Hock means to pawn, while hawk means to sell. The two homophones are sometimes mistakenly interchanged to give us the eggcorn.