Depressed mood refers to a period of feeling sad, empty, or irritable, often accompanied by a loss of interest or pleasure in activities that were once enjoyable.1

While it's a common human experience to feel down at times, a depressed mood is more persistent and can significantly affect a person's thoughts, feelings, behavior, and overall well-being.2

It's important to distinguish a depressed mood from normal sadness or grief. Sadness is a natural emotional response to disappointing or unhappy events, and grief is a natural reaction to loss.3 While both can involve feelings of unhappiness, a depressed mood that is part of a larger depressive disorder tends to be more pervasive, long-lasting, and may occur without an obvious cause. In major depression, feelings of worthlessness and self-loathing are common, whereas in grief, self-esteem is usually maintained.4

Key characteristics and common symptoms associated with a depressed mood can include:

• Persistent sadness: A low mood that lasts for most of the day, nearly every day, for at least two weeks.5
• Loss of interest or pleasure (anhedonia): Reduced interest or enjoyment in most or all activities that were previously found pleasurable.6
• Changes in appetite or weight: Significant weight loss when not dieting, weight gain, or a decrease or increase in appetite.7
• Sleep disturbances: Insomnia (difficulty sleeping) or hypersomnia (sleeping too much).8
• Fatigue or loss of energy: Feeling tired all the time, even without physical exertion.9
• Feelings of worthlessness or excessive guilt:10 Harboring negative views about oneself or feeling inappropriately guilty.11
• Difficulty thinking, concentrating, or making decisions: Impaired cognitive functions.12
• Recurrent thoughts of death or suicide: Thinking about death, having suicidal ideas, or attempting suicide.13
• Restlessness or slowed behavior (psychomotor agitation or retardation): Observable by others, such as being unable to sit still or, conversely, moving or speaking more slowly than usual.14
• Irritability or frustration: Especially in children and adolescents, a depressed mood may manifest as irritability rather than sadness.15
• Unexplained physical problems: Such as back pain or headaches.16

A depressed mood can be a symptom of various conditions, most notably Major Depressive Disorder (MDD), also known as clinical depression.17 For a diagnosis of MDD, these symptoms must be present for at least two weeks and represent a change from previous functioning, causing clinically significant distress or impairment in social, occupational, or other important areas of functioning.18

Other conditions where depressed mood can be a prominent feature include:

• Persistent Depressive Disorder (Dysthymia): A chronic form of depression where a depressed mood lasts for at least two years (one year in children and adolescents), with symptoms being generally milder but more long-lasting than in MDD.
• Bipolar Disorder: Individuals with bipolar disorder experience episodes of depression alternating with periods of mania or hypomania19 (elevated mood).20
• Premenstrual Dysphoric Disorder (PMDD): Severe mood symptoms, including depression, that occur in the week before menstruation and improve within a few days after the onset of menses.21
• Depressive disorder due to another medical condition: Some medical illnesses can cause symptoms of depression.22
• Substance/Medication-Induced Depressive Disorder: Depression symptoms that develop during or soon after substance intoxication or withdrawal or after exposure to a medication.23

The causes of depressed mood and depressive disorders are complex and multifaceted, often involving a combination of:

• Biological factors: Including brain chemistry (imbalances in neurotransmitters like serotonin, norepinephrine, and dopamine), genetics (depression can run in families), and hormonal changes.24
• Psychological factors: Such as personality traits (e.g., low self-esteem, pessimism), coping styles, and a history of trauma or abuse.25
• Social and environmental factors: Including adverse life events (e.g., loss of a loved one, unemployment, financial difficulties, relationship problems), chronic stress, lack of social support, and certain living conditions.26

If you or someone you know is experiencing a persistent depressed mood and other symptoms of depression, it is important to seek help from a healthcare professional or mental health provider for proper assessment and guidance. Effective treatments, including therapy and medication, are available.27