it is. i only did it by accident, astral projection, least i think thats what that was. doesn't happen anymore but it would always happen during naps in the daytime. every time it happened i would tell myself to be courageous next time and let it happen. each time i'd get a little further but not by much. i could go into details but they were very random and surreal.... always different. the heavy vibration and loud noise was the only thing consistent in each one. The vibrating got heavier and heavier the longer i'd let it go. It always happened at that stage you're in right before you are fully asleep. half awake per say. but each time i would snap out of it from fear. and i say 'snap out of it' because it was different than waking up. weird glitch in the brain that happens during the process of falling asleep.