First off, have you tried sleeping in a different position? Sometimes I feel that being on my stomach makes it much easier for me to be able to get up. This way right after the white noise (i call it body buzz lol) I can push myself into a standing position if need be. Have you tried using your hands to stop yourself buy grabbing onto something?
Secondly, I haven't astral traveled more than a minute myself. Although some can travel for hours or even all night! This will come with time, try to make sure there are no distractions around you, like a loved one watching television in the next room, or pets wondering around. During your trip, its important not think to much about time. Just go with the flow and enjoy. And in no time, you'll be leaving the house and visiting friends, family or even places you've never been before.
Lastly, I'm not sure about the fatigue type symptoms you mentioned. Because everytime I astral project, I jolt back into my body with my heart pounding and fall asleep. I hope someone is able to answer that for you.
edit on 7-11-2012 by Xquizit because: Grammar