It takes a few days to maybe a couple weeks for your body to get used to the long acting morphine.
When I first started on it, I slept all the time too. After a couple weeks I couldnt even tell I was taking anything accept for the fact that the pain was reduced by about 50%.
You cant really judge any med in the first few days really, gotta give your body time to adjust. If after say 5 days you are experiencing weird feelings then for sure contact your doctor.
One thing about morphine though... it slows your breathing, and when sleeping is when it is most dangerous. So your right on about contacting your doctor, it just might be you need to titrate up