Review the original item:
Carla has difficulties getting to her 8 a.m. English class on
time,
she always watches too many late night movies and then hits the snooze
button on her alarm once too often.
You wanted to fix it this way:
Carla has difficulties getting to her 8 a.m. English class on
time,
because she always watches too many late night movies and then hits
the snooze button on her alarm once too often.
By placing a because in front of she always watches, you subordinate what was a main clause. This method is a legal move in writing. There is a problem, however. When you attach a subordinate clause to the end of a main clause, you seldom need a comma.
The comma before because is the problem with this choice.
You might want to consult the rules for fixing comma splices and fused sentences.