Every once in a while. I always try to go back to sleep. Unless whatever woke me up made me forget what I was dreaming about. Then I get very depressed and almost cry, then read FanFiction cuz I'm not going back to sleep at that point.
I wake up during the night all the time. In fact, it's quite normal for me. Last night I woke up 4 times. The first time was at 3:00 AM, and the other 3 times were all around 5:00-7:00 AM. I can usually fall back asleep, but at a certain point, I'll sometimes just go ahead and get up.
I'm a pretty light sleeper but I basically never wake up in the middle of the night. Sometimes I'll wake up much earlier than in intended, but never just randomly.
This happens to me almost nightly, weekends and schooldays. I'll find myself waking up at 2 or 3 am, and at this time I'm not tired at all, and usually have a hard time falling back asleep. Usually what I'll do is log onto ZD and chat in the Shoutbox with some of the members that live overseas.
I do sometimes. I can sleep right away, but I always like to know what time it is before I go back to sleep. I usually wake up because of a nightmare I get.