A main function for sadness is to help adjust to a significant loss, such as the death of someone close or a major disappointment. Sadness brings a drop in energy and enthusiasm for life's activities, particularly diversions and pleasures, and, as it deepens and approaches depression, slows the body's metabolism. This introspective withdrawal creates the opportunity to mourn a loss or frustrated hope, grasp its consequences for one's life, and, as energy returns, plan new beginnings. This loss of energy may well have kept saddened—and vulnerable