A serious and pervasive mood disorder that is characterized by feelings of worthlessness, low energy, either increased or interrupted sleep, loss of interest in activities, social isolation, either decreased or increased appetite, difficulty with activities of daily living (bathing, brushing teeth, getting dressed), and in some cases, thoughts of suicide. An estimated 16.2 million adults—6.7 percent of the U.S. population—suffer at least one MDD episode per year (source: https://www.healthline.com/health/depression/facts-statistics-infographic).