Sleep Cycles

This is my first foray in a long time into the world of fan-fiction - specifically, a Harry Potter fanfic. It takes place at some point during Prisoner of Azkaban. Please comment on it - I'll be gone for a week, and I want to have comments when I get back.

"PARVATI! I've given you an extra five minutes already! Get up now, or I start singing!"
Hermione Granger awoke once again to the sound of her roommates' magical alarm clock. She'd bought the thing in Hogsmeade two weeks ago, and it refused to shut up until you were really out of bed. It was only a matter of time before one of the girls decided to throw it out the tower window.
Hermione did not feel like getting up. Even with just her class schedule, she'd had to be awake three hours longer than everyone else, so by the time she'd gotten through her last class yesterday she'd been ready to go to bed. Then she'd had another five hours of homework. After that she could have gone to sleep, but she'd felt obligated to finish up some work on Buckbeak's case first. When she finally got to bed, she only had three hours left until she had to get up.
In the four-poster next to hers, Parvati had finally succumbed to her alarm clock and had left the room. The rest of the girls had left some time ago. Hermione tried to rouse herself, but she just didn't have the energy. She remembered having a dream. This was odd, because she hadn't dreamt in months - she hadn't had enough sleep. She was about to force herself to get up. Then her eye caught the gleam of the time-turner on her desk.
I shouldn't, she thought. I promised McGonagall I'd only use it to get to my studies. I could get in loads of trouble!
But it is for your studies! said another voice inside of her. How are you supposed to get good marks if you can't get enough sleep? Just two more hours, it won't hurt anyone.
Hermione was far too tired to argue with herself, and the bed was so warm and comfortable. She reach over, grabbed the small gold chain, and through it over her neck. Then she gave the little hour glass two turns, and promptly fell asleep.
She awoke some time later. Something was pressing against her. It's only Crookshanks, she thought, Go back to sleep. Then she heard a muffled cry. Startled, she sad up and looked around. There was someone else in the bed with her!
Simultaneously, they turned to look at each other. As the Hermione of an hour and a half ago stared confusedly at her, she suddenly remembered the dream she'd had earlier that night - or actually, not earlier, but exactly then. Only it hadn't been a dream at all.
"What?" asked the other her confusedly.
"It's just a dream," said the more recent Hermione, "Go back to sleep,"
The other her, exhausted, did. The time traveling Hermione climbed over her own sleeping form, slid out of bed and tried to figure out what to do.
She glanced at her watch. The other girls in the dorm would be waking up in half an hour - and if they saw two Hermione's in the room, her days at Hogwarts would be over. She could go back to the common room - but then the other girls would wonder how she'd gotten there so fast. She could go straight to breakfast, but that would raise some uneasy questions about why she was up so early when she'd gone to bed so late. Eventually, she decided to hide under her bed until the other her left to go back in time and get some more sleep, then crawl out and run down to breakfast.
She waited under the bed for about half an hour, but she couldn't keep her eyes opened. After all, she'd still only had about five hours of sleep.
This time what awakened her actually was Crookshanks. She tried to sit up, and clonked her head on the bed. "
What am I doing under the bed? She thought. Then the events of the morning started to come back to her. It couldn't be, she thought, I can't have been that stupid. She decided it must have all been a dream. She glanced at her watch - It was 8:50. She ran out of the room and towards the North Tower for Divination.
She climbed up the ladder at 8:58, and sat down next to Ron.
"Hello," he said to her, "Where were you at Breakfast?"
"I guess," Hermione mused, "I just didn't have the time,"