No Caffeine

Don't know where else to blog about this, so you readers are the lucky ones.
Long story short:  I'm getting lots of medical testing done.  One of the tests is a "sleep study" to check for sleep apena.
Reading through the list of stuff to do for preparation:  not supposed to have ANY caffeine for 24 hours before the study.
First question:  does that mean for 24 hours before the study begins, which is this evening, say 9pm, so that would have been starting at 9pm last night?  Or does it mean for 24 hours before the study will end, at the unusual hour of 5:30 am tomorrow morning.  Why 5:30? 
There are so many questions here.

So, I go to a website to look up Caffeine

And the side bar add is:  Is Excessive Sleepiness Hurting You?  Take the Quiz >
And there's questions about how much coffee you drink in comparison to co-workers, do you have obligations that keep you up late or make you get up early, headaches, napping, dozing off.........
And then the anaylsis article that says the expected blanket "Americans aren't sleeping enough or well enough".
You should see your doctor for help with this problem.
This is supposed to be new information?
Sleep affects work performance?
Sleepiness can be dangerous while driving?
No Kidding!

Now my only question is:  what knitting project to take to a Sleep Study