answer: Ali was up late last night and has to meet the study group this morning, so Ali doesn't get enough sleep.
documents: #Person1#: Ali! What's the matter? Can't you wake up this morning?
  #Person2#: I was up late last night. My friend had a party. I only slept about four hours.
  #Person1#: Why didn't you stay in bed this morning?
  #Person2#: I have to meet my study group at the library. We have a big text next week.
  #Person1#: A big text? Why didn't you study last night instead of going to the party?
  #Person2#: Oh, it's OK. I studied a lot before the party.
  #Person1#: Maybe that's not a good idea. I read a report. It said that if you don't get enough sleep after you study, you may forget 30% of what you've studied!