Why do i suddenly wake up at 4:45 AM

I know this sounds bizarre, but for the third day in a row, I've been waking up suddenly at 4:45 AM. Each time, I have a vivid dream just before waking. I look around, and then fall back asleep.

On the first day, I dreamt of a haunted house. The second day, I dreamt I was working in a candy factory. Today, I dreamt I was home alone during a thunderstorm while my family was on vacation.

It's weird, and I don't know why this is happening.