What is the difference between "I can't get any sleep" and "I can/'t get no sleep"? [duplicate]

Possible Duplicate:
What does “I Can't Get No Satisfaction” mean?

I'd like to know the difference between these sentences:

I can't get any sleep.
I can get no sleep.
I can't get no sleep.

1) I can't get any sleep

2) I can get no sleep

3) I can't get no sleep

(1) and (3) mean exactly the same thing; (1) is standard, while (3) is used only in dialects of English that have negative concord, a linguistic property in which adding a second negative to a sentence serves as an intensifier (rather than cancelling the first negative and turning the meaning positive, as occurs in standard American and British English). (3) is essentially never used in writing, or anywhere outside specific speech communities - many English speakers consider this form to sound "wrong" or "uneducated", so it's best to use (1) instead.

(2) is a grammatical sentence in standard English, but sounds strange and would be rarely used. It also has two possible meanings (it is ambiguous), depending on context. It could mean the same thing as (1); if this is your intent, use (1), as it sounds much more natural. However, it could be that in contrast to (1) which asserts the speaker's inability to sleep, (2) asserts the speaker's ability to not sleep. Consider the following hypothetical conversation:

Person A: I can't pull an all-nighter, I'll be dead in the morning. I need at least a few hours of sleep to function.

Person B: I don't know what you're talking about. I can get no sleep and feel just fine.

In this case (2) means something definitely distinct from (1); Person B is saying she is able to go without sleep, not that she is unable to sleep. However, note that some context such as the above is necessary for this reading to make sense; "I can get no sleep" in isolation is hard to interpret this way, and just sounds odd.

The first two are grammatical in Standard English. The second is much less likely to be found than the first, which is itself less likely than I can’t get to sleep. The third shows double negation, a feature that was for centuries a normal part of the language, but which is grammatical now only in non-standard varieties of English.