I would like to know why my friend (ha ha but it's true) can't stay
asleep for a full night when she drinks alchohol.  She says she
typically wakes up after about two or three hours.  Is there a cutoff
point before bed that she should stop drinking?

Does she wake up because she has to go to the bathroom (a healthy reason)?

If so, probably if she stopped drinking an hour or two before going to
bed, and went just before doing so, she wouldn't wake up.

I seem to recall that ages ago I read people wake up when the booze
finishes being processed out of the system.

Hi Mark,
Maybe you read that somewhere, but not from anyone who ever woke up with hangover.

But I am not suggesting that the lady in question may be.

Cheers, Myoarin

It sounds to me as if she is not drinking enough.

Facetiousness aside, I think there's some research that indicate that
drinking disrupts (I think) the REM stage of sleep, leading some to
have an overall more fitful or less restful sleep.

The article at http://alcoholism.about.com/cs/alerts/l/blnaa41.htm
might be a good starting place in hunting down more specific
information.

if she is drinking sugar filled drinks, or coke as a mixer, this may
be any explanaion

all the alcohol in her blood could be waking her.It would just be
better if she didnt drink at all!!