Bipolar disorder involves extreme shifts in mood between periods of mania and depression. During mania, people may feel euphoric, irritable, have racing thoughts, sleep little, spend excessively, and engage in risky behaviors. Depression brings feelings of hopelessness, guilt, fatigue, changes in appetite and sleep, and suicidal thoughts. Bipolar disorder is thought to have genetic and environmental triggers and can be managed through medication and lifestyle changes to recognize and cope with mood shifts.