Prolonged stress or trauma
People who suffer from traumatic and stressful events in their childhood are also more likely to suffer from bipolar disorder at some point in their lives. As the people going through prolonged stress suffer from a genetic vulnerability which makes them more prone to develop mania and depressive episodes of bipolar disorder. Stressful events like losing a loved one, rape, or getting fired tend to cause sudden or drastic changes in mood of the suffering person and triggers mood swings.