Awaking at 2 a.m.

Since I went back to yoga early this month, I have nights that my mind would suddenly wake up in the middle of the night like 2 or 3 a.m. and have this feeling that I had already enough sleep for the day. Of course, I tried to go back to sleep and just close my eyes. Don't get me wrong, I have no problem getting asleep but when I do sleep at around 10 p.m or so on some nights I wake up and would feel like I already had a good night sleep in just a short time. Was it just me? Hmm... I don't know if other yogis feel the same... Will you tell me if you have experienced what I've been experiencing?