Read the following context and choose the best option to answer the question.
Context: Woke up at 3:30 am , could n't get back to sleep . It sucks . Two days ago I was still drowsy and sleeping all the time . I still want to sleep all the time , but it is not happening .
Question: What may be the reason I can not go to sleep ?
Options: 
A. I have to work nights ,
B. I have insomnia .
C. I have to study .
D. None of the above choices .


B