Depression

Depression includes persistent sadness, loss of interest, changes in sleep or appetite, fatigue, and feelings of worthlessness. These symptoms must last most of the day, nearly every day, for at least two weeks to meet clinical criteria. Unlike normal sadness, depression interferes with daily function and does not improve with time alone. People often report difficulty concentrating, making decisions, or engaging in routine responsibilities.

Biological factors include genetics, neurotransmitter imbalances, and medical conditions like thyroid disorders or chronic pain. Environmental triggers often involve major life changes, trauma, loss, or ongoing stress such as financial hardship or relationship strain. Some individuals experience seasonal patterns, with symptoms worsening in fall or winter due to reduced sunlight exposure, a feature recognized as seasonal affective disorder.

Seek help if symptoms last more than two weeks, disrupt work or relationships, involve hopelessness or thoughts of self-harm, or persist despite self-help efforts. A primary care provider or mental health clinician can conduct a full assessment and rule out medical causes. Treatment often combines psychotherapy and medication, with many experiencing significant symptom relief within weeks of starting care.