Bipolar disorder causes extreme shifts in mood from depression to mania. The document discusses the symptoms of mania like feeling over energetic, irritable, reckless, and having rapid speech. Depressive symptoms include feeling hopeless, worthless, and having suicidal thoughts. Treatment involves avoiding substance abuse, psychotherapy, medication like lithium, and hospitalization during severe episodes. The author has experienced depression, hypomania, and suicidal thoughts related to their bipolar disorder and stress at work.