It normally becomes night as the day goes on.

You can still play until you go to bed.
If you want to sleep change the alarm clock in your cell phone to 6 AM.
Remember that you have to be in your bedroom at 11 PM so that you don't get a demerit.
You can can get Rachel's after having all the other 5 pictures in your camera and loaded in the web page. Then you can ask Rachel for her picture.
Leela will ask you to play if you ask her about Megan's picture.
You can ask for Megan's picture only after Mel tells you that Leela has one and also call Megan using your cell phone.