A 15-year-old boy is brought in by his mother, who reports h…

A 15-year-old boy is brought in by his mother, who reports he has been “moody” for the past 6 months. He has periods of irritability lasting several hours after conflicts with friends, followed by normal mood the next day. He maintains good sleep, grades, peer relationships, and extracurricular participation. He denies impulsivity, decreased need for sleep, or sustained elevated mood. Which diagnosis is MOST consistent with this presentation?