Guys can anyone explain this?

One time, I was woken up by my mom around 7:45, and i was still tired, so i slowly dozed off. Five seconds later, i had my parents yelling at me to get up because id slept 25 extra minutes and it was 8:00. Another time it was essentially the same thing, i set and alarm for 7:00, woke up, went back to sleep for "five minutes" and fifteen seconds later woke up at 7:20 something. Does anyone have an explanation fo this? ​