Wow.. I've been struggling with the 4am wakies as well!!! For about 2 months now!!!
I have recently started hypnotherapy and my therapist has suggested journalling - it is funny how you can wake up and know something is wrong, but it takes me writing for a good half hour to start to dig into these issues and start to put them into perspective.
With respect to WHY we wake up at 4am.. I asked my therapist - as she practices hypnotherapy she's an expert on brainwaves. She explained that if you are currently struggling with anxiety/panic you will likely wake up almost exactly 4 hours from the time you went to sleep, as that is when the first REM period (dream state) ends and it is actually fairly normal to awaken at this time of the night. Most people wake up for about 30 seconds, but most people dont remember this and fall right back to sleep again.
However, it is very difficult for anxiety sufferers to keep the "scaries" at bay after the first REM cycle. The brain has been quieted for awhile, and while we have been sleeping we are not expending the energy to keep our fears crushed down. (It takes a LOT of energy to manage anxiety!!). Therefore, the brain starts to release the fears, and BAM we cant get back to sleep!!! Our minds are racing, etc. Heh.. over the past few weeks I have rearranged my room, cleaned my apartment several times over, gone for a drive, even went to my office to put some stuff away, all between 4 and 6 am!!!
FYI my BF (SA survivor) SWEARS by journalling - and I am starting to be a big fan of it. He finds it allows him to make sense of his thoughts and figure out what he is REALLY feeling, so he can try and devise a way to deal with it.
Why not write in your journal when you wake up at 4am? I have titled my journal the "4 am chronicles"...
Probably better than watching the cheesy infomercials on the tube at 4am (I'm getting sick of watching Anthony Robbins hawk his "personal power" tapes!!!)