A 27-yrs-old woman has been feeling low for the past 2 weeks. She has little energy and has trouble concentrating. She states that 6 weeks ago she had been feeling very good, with lots of energy and no need for sleep. She states this pattern has been occurring for at least the past 3 years, though the episodes have never been so severe that she couldn't work. Most likely diagnosis is?
Borderline personality disorder Seasonal affective disorder Cyclothymic disorder Major depression, recurrent