Mood Changes: Causes and When to Get Help

What counts as a mood change

Everyone's mood varies. A mood change becomes a concern when it is:

• lasting: most of the day, nearly every day, for 2 weeks or more
• out of proportion to what is happening
• affecting function: work, study, relationships or self-care
• noticed by others as unlike you

Mood changes can go in different directions: low mood and hopelessness, irritability and anger, anxiety and worry, emotional flatness, or unusually high, energetic or reckless mood. Rapid swings within a day are covered on mood swings.

Common causes

Stress, sleep and lifestyle

Ongoing stress, lack of sleep, shift work, alcohol, cannabis and stopping caffeine or nicotine all change mood. Poor sleep alone can cause irritability, low mood and anxiety within days.

Grief and life events

Bereavement, relationship breakdown, job loss and illness commonly cause sadness, anger and numbness. Grief usually comes in waves and eases gradually over months.

Depression

Depression causes persistent low mood or loss of interest for at least 2 weeks, with changes in sleep, appetite, energy and concentration, and feelings of guilt or worthlessness. In men and teenagers, it often shows as irritability and anger rather than sadness.

Anxiety

Anxiety disorders cause persistent worry, tension, irritability, restlessness and poor sleep.

Bipolar disorder

Bipolar disorder causes episodes of depression alternating with mania or hypomania: elevated or irritable mood, needing little sleep, racing thoughts, rapid speech, and impulsive spending or behavior. Episodes last days to months.

Hormonal causes

Mood changes in women

• Premenstrual syndrome: irritability, low mood, anxiety and tearfulness in the 1 to 2 weeks before a period, easing within a few days of it starting. See premenstrual syndrome.
• PMDD: a severe form, with intense mood symptoms that disrupt life every cycle.
• Pregnancy and postpartum: "baby blues" in the first 2 weeks after birth are common and mild. Postpartum depression is more severe and lasts longer.
• Perimenopause: fluctuating estrogen in the years before menopause brings irritability, anxiety, low mood and poor sleep.
• Hormonal contraception: some people notice low mood, especially with progestin-based methods.

Other hormonal causes

• Thyroid disease: an overactive thyroid (hyperthyroidism) causes anxiety, irritability and restlessness; an underactive one causes low mood, fatigue and slowed thinking.
• Low testosterone in men can cause low mood and irritability.
• Cushing syndrome and adrenal problems, and fluctuating blood sugar in diabetes.

Medical and medication causes

• Medicines: corticosteroids (mood elevation or depression), isotretinoin, some beta blockers, interferon, levetiracetam, montelukast, hormonal treatments and withdrawal from antidepressants or benzodiazepines.
• Brain conditions: stroke, head injury and concussion, brain tumors, multiple sclerosis, Parkinson's disease and epilepsy.
• Infections: urinary or chest infections in older adults can cause sudden confusion and mood change (delirium).
• Vitamin deficiencies: B12 and folate.
• Chronic pain and serious illness.

Mood changes in older adults

New mood or personality change later in life deserves careful assessment. Depression in older adults often shows as irritability, withdrawal, physical complaints and memory problems. Dementia can begin with apathy, irritability, anxiety or uncharacteristic behavior, before obvious memory loss, especially frontotemporal dementia. A sudden change over hours to days suggests delirium from infection, dehydration or medicines and needs same-day care.

How doctors find the cause

A doctor will ask what has changed, for how long, how it affects your life, sleep, appetite, alcohol and drug use, medicines, menstrual pattern and family history of mood disorders. They may use questionnaires such as the PHQ-9 and GAD-7, and ask directly about thoughts of self-harm. Blood tests may include thyroid function, blood count, B12, glucose and sometimes hormones. Memory testing and brain imaging are used when dementia or a brain condition is suspected.

Treatment and self-help

• Talking therapies: cognitive behavioral therapy and other therapies are effective for depression, anxiety and many mood problems.
• Medicines: antidepressants, mood stabilizers for bipolar disorder, and hormonal treatments for PMDD or perimenopause where appropriate.
• Treating physical causes: thyroid treatment, stopping or switching a medicine, treating infection.
• Self-help: regular sleep and wake times, daily physical activity, daylight exposure, cutting down alcohol, staying connected with people, and tracking mood alongside your cycle, sleep and stress to spot patterns.

Frequently asked questions

What causes sudden mood changes?

Sudden mood changes can follow stress, poor sleep, alcohol or drugs, hormonal shifts and new medicines such as steroids. A sudden change with confusion, headache, fever or after a head injury may be a medical problem such as delirium, infection or a brain injury and needs urgent care.

What causes mood changes in women?

Hormonal changes around periods (PMS and PMDD), pregnancy, after birth, and in perimenopause commonly affect mood. Thyroid problems, hormonal contraception, stress and depression are other causes. Tracking mood against your cycle helps identify a hormonal pattern.

When are mood changes a sign of a mental health problem?

When low, anxious, irritable or elevated mood lasts more than 2 weeks, keeps returning, is out of proportion to events, or affects work, relationships or self-care. Thoughts of self-harm always need prompt help: call or text 988 in the US.

Can mood changes be a sign of dementia?

Yes. Apathy, irritability, anxiety, depression and uncharacteristic behavior can be early signs of dementia, sometimes before memory loss is obvious. New personality change in an older adult should be assessed by a doctor.

Can thyroid problems cause mood changes?

Yes. An overactive thyroid causes anxiety, irritability, restlessness and poor sleep. An underactive thyroid causes low mood, tiredness and slowed thinking. A simple blood test checks thyroid function, and treatment usually improves mood.