A 19 year-old woman is brought to psychiatry outpatient by her boyfriend for depression and suicidal thoughts. Boyfriend repos that patient yesterday expressed extreme sadness and desire to die. The boyfriend repos that they along with couple of friends were paying for last three days as exams had ended and on fuher prodding revealed that they used alcohol and 'other things' too. He fuher repoed that patient was in great spirits and was enjoying till yesterday, however subsequently she slept for 20 hours, missed the college and was looking very tired. The patient herself repoed that she is feeling very low, and feeling hungry and that she saw very vivid and upsetting dreams during the sleep? Which of the following is the most likely diagnosis in this patient?