So I've been housesitting for the last 12 days, and the room I was staying in had a window pointing to the east, so I'd see the light from the sun every morning. My room at my home doesn't have any windows at all and is in the basement, so it's dark all the time. At my house I often sleep in until 10:30, but at the house I was sitting at I was waking up at 8am.
Sunrise times here is about 7:46, but since we're at the foot of a mountain on our east, we get the sun when it's done getting over the top of the mountain, so a little after 8am.
Today was my first day back home, and this morning I woke up at 8:04 am, the SAME time I had been waking up at the house I was sitting at every morning due to the sun. My room is always dark, so I was just waking up at that time due to the habit I got over almost two weeks.