coudn't sleep

Not much; but "get off to sleep" means falling asleep....you might fall asleep for a brief period, then wake up. Then you may truthfully say "I couldn't sleep last night"...even though you fell asleep initially.

Thanks, Mc Tag

If I could not fall asleep at all, I could also say "I coudn't sleep last night." Am I correct?

Yes, quite correct.

Hi Mc Tag

Thanks for your help.

I hope you don't mind me asking a question not related to my present post.

You wrote: Yes, quite correct.

I believe your meaning of 'quite' is 'perfectly'. 'Quite' can also mean 'fairly', if I'm not wrong. What I'm concerned is how to use the word 'quite' so that it is clear that mean 'fairly',

Should I start a new thread on this word?

You've hit on a strange anomoly, which has been mentioned here before (by me, actually!)

"Quite" has two opposite meanings: completely, and not completely. Strange, but true.

You will have to rely on the context to indicate the meaning you want.
It doesn't cause any problems in practice.
I'm quite sure about that.

It's worth noting here, that "correct" is absolute. So "quite" used here means "completely".

But you're right, if I said something was "quite clean", it would mean that it was still a bit grubby.

correction: Anomaly is spelled this way, sorry.

Thanks. Mc Tag.