Lonely night

Another lonely night.  Seem to be having those alot lately.
Went to bed around midnight but only slept for an hour before I was too awake to fall back to sleep.
After a couple of hours of gaming I'm now lonely.  Least I think that's what this is.
I've noticed lately A LOT of mouth twitching.  I THINK its most prominent when there's nothing in my mouth and I'm concentrating.
You can see it here...
Looking at various medical stuff online there seems to be a common consensus that it can be caused by caffieine intoxification.
According to FDA 400mg is the max suggested daily dosage.
However, as the chart below shows what that means can vary GREATLY.

I drink 1 - 1.5 pots of coffee per day and close to a 6 pack of diet pepsi per day.
If you spread that out over a 14hr day then thats roughly 430mg - 1450mg / day.  But then you have to factor in the half life.
And why such a huge variance in caffeine amounts?  50-235 is a HUGE gap.
According to Maxwell house...
And Pepsi ...
Seems to indicate ~= 1000mg / day. or roughly 100mg Δ / hr.

prima facie it seems fine.  But then again you have to include the fact that the variance is so large.  If the half life is 9hrs instead of 1.5 then intoxication seems indicated.
The body is so strange.