Pam,
 
I can't say what is causing the sleep problems other than to be OFF at
bedtime makes it difficult to sleep.   I use melotonin once in a while.  It
works for me, but it is not a "knock out" drug.
 
As for the dementia, I do not want to give you unwarranted hope.  But there
are conditions that are not dementia, but may be diagnosed as such.  I do not
know what the medical profession uses for its definition of this state, but
let me discus those states that look like dementia.
 
The most obvious state that looks like we have lost our marbles is when we
are in a relatively deep OFF state.  We have a masked facial expression,
stooped posture, very slow movement if any.  Our voice is low and we talk
little, maybe just grunt.  The mind is sharp but it is locked inside of the
skull without a means to express itself.  I would not expect a listener to
think much of a thesis on relativity from a person in this state even if they
could get it out.  The obvious resolution would be to remove the OFF state.
 
The above paragraph can also be all the symptoms of a major depression.  From
the masked expression to OFF state with Parkinson's medications.  It depends
often which door the patient enters: a neurologist may see PD with dementia,
a psychologist may see severe depression with dementia.
 
Often treating only one side, say for depression, may not be sufficient.  The
doctor may treat both the Parkinson s and the depression together by
increasing medications for both.
 
A third possibility has to do with an excess amount of carbidopa.  Your
mother is taking 8 x 25/100 plus a 25/100 CR.  This is jut over 200 mg of
carbidopa daily.  I have found that I need about 100 - 150 mg of carbidopa
daily.  Any more will erode the value of additional levodopa.  I get a kind
of "drugged" feeling when I over do the carbidopa.  The resulting levodopa is
many times of only marginal value.  What I would suggest is splitting her
regular Sinemet between 25/100 and 10/100 pills.  This will drop the
carbidopa down around the 150 mg mark.  Hopefully she will have more ON time.
 
 I am not a doctor, but I play one on the list server.   There are a number
of prominent Parkinson s disease specialists on this list  server.  Ethics
along with good medical practice limits their ability to comment on patient
conditions before they have the opportunity to examine the patient which
makes sense.
 
I do hope I have not given you false hope for the dementia in your mother.  I
just feel that we are all quick to diagnose reduced mental capacity in the
elderly.  Please discuss my suggestions with your doctor.  Just don t give
her up yet.
 
Regards,
Alan