It's difficult. Almost impossible. Strange thing is that when people are awake, or even just falling asleep, waking up early seems so easy. they have to wake up at 9:00 o' clock? So what? They just set the alarm at 8:30. Stay in bed for 20 mins. Get up at 8:50. There. 10 minutes earlier.
Except it never goes according to plan. More often than not the alarm goes often at 8:30 [right on time]. People stay in bed for 20 minutes just to get used to the idea of waking up. But you never do. They fall asleep again.
A few times, somebody manages to wake up early. However, the only thought that occupies his mind [at least for 1 or 2 hours], is when they are going to sleep again.