Upvote:2
If you practice samatha for any length of time, that will happen fairly frequently especially in a retreat situation. One of the key points of samatha practice, after all, is the dropping off of body and mind. Sleep does that rather effectively though we are rarely conscious for the event. If you are suddenly awakened, there is a often a gap before mind and body reassert themselves. Related to that, what you are experiencing is also the reason why it's better to sit first thing in the morning. You sort of get to ride that gap a little bit. The waters of your mind haven't yet been muddied with all the detritus that normally gets kicked up as you go about your day.