In a traditional model of bipolar disorder, a mood episode (depression/mania/hypomania) lasts (untreated) for a prolonged period of time. Typically, an episode will last from weeks to months. In a traditional model, people with untreated bipolar disorder only experience three or fewer mood episodes per year.
To many people that actually sounds like a great blessing because, for many people, mood changes come far more rapidly. People who experience more than three mood episodes per year have what’s known as rapid cycling bipolar disorder. People who have moods that only last days have ultra-rapid cycling bipolar disorder.
And people whose bipolar moods last less than that? That’s known as ultradian cycling bipolar disorder.