How long must you sleep to get accurate results on a sleep test?

I have been diagnosed with a deviated septum, and am undergoing surgery for it at the beginning of next year. I informed my doctor about these headaches I've been having in the morning. Well they're a little different from headaches, more like pressure above my eyes. I find the longer I sleep the worse they become. Also after sleeping about six hours I find it impossible to go back to bed without waking up at least every hour. I had a sleep test done, but according to that I didn't have sleep apnea. I'm wondering if the results could be wrong seeing as I was only able to sleep for about half an hour and they must not have been able to collect enough data. Could this pressure above my eyes be a sign of sleep apnea, or could they just be due to my deviated septum? I also find I don't really get overly sleepy in the day, however if I'm lying down and watching T.V or reading I will dose off.

( had two sleep apnea tests performed. The technicians need at least 6 hours of your sleeping to get accurate results.
Pressure above your eyes is not a sign of sleep apnea.

The pressure above your eyes could be caused by allergies or a (deep) sinus infection (I have also had this pressure..it is only slightly painful whenI I strongly pressed the area right below the eyebrow) .
I also had a deviated septum and had it fixed years ago. They fixed the septum, also took out a blockage of tissue and bone. It made a world of difference.

I still get the pressure just above the eyes when my deep sinuses get infected (a fixed septum doesn't make a person immune to sinus infections, only perhaps less likely to get one).