'tend to wake up at about 2.5 hour intervals'

Fletcher -- my husband has sleep apnea - and this is something I've heard HIM say -- he would wake up every couple of hours - sometimes just a bit - and sometimes wide awake. He felt fine most of the time, but sometimes wore out b/c he wasn't getting REM sleep. He was diagnosed with Sleep Apnea and currently uses a CPAP machine.

If you are only sleeping 2.5 hours at a time, you might seriously consider taking a sleep test to rule out sleep apnea. Your body makes you wake up because you aren't getting oxygen into it -- it's a survival thing.

Good luck!