Identifying Bipolar I Disorder Symptoms

Alice is a 28-year-old woman who frequently experiences mood fluctuations that range from severe irritability to episodes of euphoria. Her friends have noted that during her euphoric phases, she takes on numerous projects and stays awake for days, barely needing sleep. However, during her low periods, she tends to isolate herself and expresses feelings of hopelessness. Considering her behavioral patterns and emotional state, what psychological disorder is most likely affecting Alice?