Falling Asleep is Easy...

Staying asleep is the hard part for me. It's 2 AM here, I fall asleep, sleep for an hour or so then wake up. It goes on all night like this. Doctor added 0.5mg of Klonopin yesterday and told me to take it at bed time, that it should help with my sleep an anxiety. Is anyone else taking Klonopin? Does it take time to build up in your system or should I call the doctor and ask for higher dose?

Klonopin has a half life of 30'ish hours, but most users report that it's effective from about 4-6 hours. It could be that your dose is small enough that it has a initial impact, but quickly gets below a therapeutic dose (for you). I'd recommend two things:
(1) see your doctor about increasing the dose in the short term
(2) try to get off it altogether - see this video http://www.benzo.org.uk/nicks.htm
I became "physically dependent" on another benzodiazpine (lorazepam/Ativan) and it was hell to finally get off it.