The criteria below are based on the formal DSM-V criteria for a<unk> . A diagnosis of<unk>  requires that the patient has experienced five or more of the symptoms below, and one of the symptoms must be either depressed mood or loss of interest of pleasure (although both are frequently present). These symptoms must be present for at least 2 weeks and represent a change from the patient's normal behavior. Depressed mood and loss of interest (anhedonia) Either depressed mood or a loss of interest or pleasure must be present for the diagnosis of a<unk> . Depressed mood is the most common symptom seen in<unk> s. Interest or pleasure in everyday activities can be decreased; this is referred to as anhedonia. These feelings must be present on an everyday basis for two weeks or longer to meet DSM-V criteria for a<unk> . In addition, the person may experience one or more of the following emotions: sadness, emptiness, hopelessness, indifference, anxiety, tearfulness, pessimism, emotional numbness, or irritability. In children and adolescents, a depressed mood often appears more irritable in nature. There may be a loss of interest in or desire for sex, or other activities once found to be pleasant. Friends and family of the depressed person may notice that they have withdrawn from friends, or neglected or quit doing activities that were once a source of enjoyment. Sleep Nearly every day, the person may sleep excessively, known as hypersomnia, or not enough, known as insomnia. Insomnia is the most common type of sleep disturbance for people who are clinically depressed. Symptoms of insomnia include trouble falling asleep, trouble staying asleep, or waking up too early in the morning. Hypersomnia is a less common type of sleep disturbance. It may include sleeping for prolonged periods at night or increased sleeping during the daytime. The sleep may not be restful, and the person may feel sluggish despite many hours of sleep, which may amplify their<unk>  symptoms and interfere with other aspects of their lives. Hypersomnia is often associated with an atypical depression, as well as seasonal affective disorder. Feelings of guilt or worthlessness Depressed people may have feelings of guilt that go beyond a normal level or are delusional. These feelings of guilt and/or worthlessness are excessive and inappropriate.<unk> s are notable for a significant, often unrealistic, drop in self-esteem. The guilt and worthlessness experienced in a<unk>  can range from subtle feelings of guilt to frank delusions or to shame and humiliation. Additionally, self-loathing is common in clinical depression, and can lead to a downward spiral when combined with other symptoms. Loss of energy Persons going through a<unk>  often have a general lack of energy, as well as fatigue and tiredness, nearly every day for at least 2 weeks. A person may feel tired without having engaged in any physical activity, and day-to-day tasks become increasingly difficult. Job tasks or housework become very tiring, and the patient finds that their work begins to suffer. Decreased concentration Nearly every day, the person may be indecisive or have trouble thinking or concentrating. These issues cause significant difficulty in functioning for those involved in intellectually demanding activities, such as school and work, especially in difficult fields. Depressed people often describe a slowing of thought, inability to concentrate and make decisions, and being easily distracted. In the elderly, the decreased concentration caused by a<unk>  may present as deficits in memory. This is referred to as pseudodementia and often goes away with treatment. Decreased concentration may be reported by the patient or observed by others. Change in eating, appetite, or weight In a<unk> , appetite is most often decreased, although a small percentage of people experience an increase in appetite. A person experiencing a<unk><unk>  may have a marked loss or gain of weight (5% of their body weight in one month). A decrease in appetite may result in weight loss that is unintentional or when a person is not dieting. Some people experience an increase in appetite and may gain significant amounts of weight. They may crave certain types of food, such as sweets or carbohydrates. In children, failure to make expected weight gains may be counted towards this criteria. Overeating is often associated with atypical depression. Motor activity Nearly every day, others may see that the person's activity level is not normal. People suffering from depression may be overly active (psychomotor agitation) or be very lethargic (psychomotor retardation). Psychomotor agitation is marked by an increase in body activity which may result in restlessness, an inability to sit still, pacing, hand wringing, or fidgeting with clothes or objects. Psychomotor retardation results in a decrease in body activity or thinking. In this case, a depressed person may demonstrate a slowing of thinking, speaking, or body movement. They may speak more softly or say less than usual. To meet diagnostic criteria, changes in motor activity must be so abnormal that it can be observed by others. Personal reports of feeling restless or feeling slow do not count towards the diagnostic criteria. Thoughts of death and suicide A person going through a<unk>  may have repeated thoughts about death (other than the fear of dying) or suicide (with or without a plan), or may have made a suicide attempt. The frequency and intensity of thoughts about suicide can range from believing that friends and family would be better off if one were dead, to frequent thoughts about committing suicide (generally related to wishing to stop the emotional pain), to detailed plans about how the suicide would be carried out. Those who are more severely suicidal may have made specific plans and decided upon a day and location for the suicide attempt. Comorbid disorders<unk> s may show comorbidity (association) with other physical and mental health problems. About 20–25% of individuals with a chronic general medical condition will develop major depression. Common comorbid disorders include: eating disorders, substance-related disorders, panic disorder, and obsessive-compulsive disorder. Up to 25% of people who experience a<unk>  have a pre-existing dysthymic disorder. Some persons who have a fatal illness or are at the end of their life may experience depression, although this is not universal.
Major depressive episode
Major depressive disorder
Outline of bipolar disorder
Depression 
Late life depression
Atypical depression
Postpartum psychosis
Postpartum depression