Despite much research investigating the causes of depression, there is still a lot that is unknown. We do know there are a number of things linked to its development, including biological, psychological, social, and environmental elements. Stressful life events - including but not limited to emotional, verbal, physical and sexual abuse and neglect; long-term isolation or loneliness; difficult life changes or transitions; prolonged work stress; loss of a loved one or other forms of grief and loss; relationship conflicts, or financial difficulties. Personal factors - such as a tendency to worry, low self-esteem, perfectionism, tendency to avoid feelings, self-criticism, pessimism, and other negative thinking patterns. ​ Changes in the brain - according to scientific research, depression is not simply the result of a 'chemical imbalance' like having too much or not enough of a particular brain chemical. The way your brain regulates mood can be affected by many things, including the severity of life stressors,  medications, drugs and alcohol use, medical conditions, genetic factors and whether your body is being provided with its basic needs for nutrition, rest, sleep and exercise. While they are not the sole cause, there is substantial research supporting the link between hormonal changes, particularly the drop in estrogen and progesterone after childbirth, and the onset of postnatal depression. Chronic Illness: Physical health conditions, such as chronic pain, cardiovascular disease, diabetes, and cancer, increase the risk of depression. Substance Use: Alcohol and drug abuse or dependence can worsen or trigger depression symptoms. Sleep Disturbances: Insomnia or disrupted sleep patterns are common in depression and can both contribute to and result from depressive symptoms. Cultural and Societal Factors: In many cultures and societies, there is an unbalanced emphasis on self-reliance, perfectionism, and the pursuit of success, which can foster self-criticism and contribute to poor mental health. Pressures related to success, appearance, and gender can heighten stress and increase the risk of depression. Additionally, harmful and inaccurate beliefs about mental health can make individuals feel invalidated, weak or ashamed for experiencing these issues, and may prevent them from seeking help, leading to prolonged and untreated depression.