What Is Depression?

Medically Reviewed by Jennifer Casarella, MD on September 19, 2022
9 min read

Depression, also known as major depressive disorder or clinical depression, is a mood disorder with a group of symptoms including constant sadness or lack of interest in life.

Most of us feel sad, lonely, or depressed at times. It's a normal reaction to loss, life's struggles, or injured self-esteem.

But when intense sadness -- including feeling helpless, hopeless, and worthless -- lasts for many days to weeks and keeps you from living your life, it may be something more than sadness. That's when it's time for you to seek medical help.

Your regular doctor is a good place to start. They can test you for depression and help manage your symptoms. If your depression goes untreated, it may get worse and last for months, even years. It can cause pain and possibly lead to suicide, as it does for about 1 of every 10 people with depression.

Recognizing the symptoms is key. Unfortunately, about half the people who have depression never get diagnosed or treated.

They can include:

  • Trouble concentrating, remembering details, and making decisions
  • Feelings of guilt, worthlessness, and helplessness
  • Pessimism and hopelessness
  • Insomnia, early-morning wakefulness, or sleeping too much
  • Crankiness or irritability
  • Restlessness
  • Loss of interest in things once pleasurable, including sex
  • Overeating or appetite loss
  • Aches, pains, headaches, or cramps that won't go away
  • Digestive problems that don't get better, even with treatment
  • Persistent sad, anxious, or "empty" feelings
  • Suicidal thoughts or suicide attempt
  • Lose pleasure in life

While these symptoms are common, not everyone with depression will have the same ones. How severe they are, how often they happen, and how long they last can vary.

Your symptoms may also happen in patterns. For example, depression may come with a change in seasons (a condition formerly called seasonal affective disorder).

If you have depression, it can also cause you physical symptoms. Those may include joint pain, back pain, digestive problems, sleep trouble, and appetite changes. You might have slowed speech and movements, too. The reason is that your brain chemicals linked to depression, specifically serotonin and norepinephrine, play a role in both mood and pain.

Childhood depression is different from the normal blues and everyday emotions most kids feel. If your child is sad, it doesn’t mean they have depression. But when their sadness stays day after day, depression may be an issue. Disruptive behavior that interferes with normal social activities, interests, schoolwork, or family life may also be signs of depression.

A lot of teens feel unhappy or moody. But if your teen’s sadness lasts for more than 2 weeks and they have other symptoms of depression, there may be a problem. Watch for their withdrawal from friends and family, a drop in their performance at school, or use of alcohol or drugs. Talk to your doctor and find out if your teen may be depressed. There’s  effective treatment that can help them move beyond depression as they grow older.

Doctors haven’t pinpointed the exact causes for depression. They think it may be a combination of things, including:

  • Brain structure. People with depression seem to have physical differences in their brains from people who don’t have depression.
  • Brain chemistry. Chemicals in your brain called neurotransmitters play a part in your mood. When you have depression, it could be because these chemicals aren’t working the way they should.
  • Hormones. Your hormone levels change because of pregnancy, postpartum issues, thyroid problems, menopause, or other reasons. That can set off depression symptoms.
  • Genetics. Researchers haven’t yet found the genes that might be responsible for depression, but you’re more likely to have depression if someone you’re related to has it.

Different types of depressive disorders your doctor can diagnose include:

  • Unipolar major depression
  • Persistent depressive disorder, also called dysthymia, when depression lasts for at least 2 years.
  • Disruptive mood dysregulation disorder, when children and teens get very cranky, angry, and have intense outbursts that are more severe than a typical reaction
  • Premenstrual dysphoric disorder, when you have severe mood problems before your period, more intense than typical premenstrual syndrome (PMS)
  • Substance-induced mood disorder (SIMD), when symptoms happen while you’re taking a drug or drinking alcohol or after you stop
  • Depressive disorder due to another medical condition
  • Other depressive disorders, such as minor depression

Your depression may have other specific features, such as:

  • Anxious distress. You worry a lot about things that might happen or about losing control.
  • Mixed features. You have both depression and mania -- periods of high energy, talking too much, and high self-esteem.
  • Atypical features. You can feel good after happy events, but you also feel hungrier, need to sleep a lot, and are sensitive to rejection.
  • Psychotic features. You believe things that aren’t true, or see and hear things that aren’t there.
  • Catatonia. You can’t move your body normally. You might be still and unresponsive or have uncontrollable movements.
  • Peripartum depression. Your symptoms begin during pregnancy or after giving birth.
  • Seasonal pattern. Your symptoms get worse with changes in the seasons, especially in colder, darker months.

Depression can be a symptom of other health conditions. It's important you get the right diagnosis and the best treatment. Some disorders that can cause depression include:

  • Bipolar I and II disorders. These mood disorders include swings of highs (mania) to lows (depression). It can be tricky to tell the difference between bipolar disorder and depression.
  • Cyclothymic disorder. This involves mood swings that are milder than those of bipolar disorder.
  • Other depression disorders. These include depression caused by the use of recreational drugs, some prescribed medications, or another medical condition.

To decide if you have depression, and what type, your doctor will use:

  • Physical exam. They’ll check your overall health to see if you might be dealing with another condition.
  • Lab tests. You may have bloodwork done to check certain hormone levels.
  • Psychiatric evaluation. Your doctor will check your mental health. They’ll ask about your thoughts, feelings, and behavior patterns. You may also fill out a questionnaire.
  • "Diagnostic and Statistical Manual of Mental Disorders" (DSM-5). The American Psychiatric Association lists the criteria for depression in this manual. Your doctor may use it to help make a diagnosis.

There’s no cure for depression. Your symptoms may go away over time, but the condition won’t. But with care and treatment, you can reach remission and enjoy a long, healthy life.

It’s common for people to have other medical or mental health problems along with depression, such as anxiety, obsessive compulsive disorder, panic disorder, phobias, substance use disorders, and eating disorders. If you have symptoms of depression or another mental illness, talk to your doctor. Treatments can help.

Research shows 7% of women in the U.S. experience depression during their pregnancy. Studies suggest that rate may be higher in lower income countries.

Because depression symptoms like changes in your sleep, energy level, appetite, and libido can be common in anyone who’s pregnant, your doctor may miss diagnosing your depression during pregnancy.

You’re at higher risk for depression during your pregnancy if you have:

  • Anxiety
  • Life stress
  • History of depression
  • Poor social support
  • Unintended pregnancy
  • Intimate partner violence

The American College of Obstetricians and Gynecologists recommends you be screened for depression and anxiety at least once during your pregnancy. In that screening, your doctor will ask you questions about your mood and anxiety.

But if you think you have depression, don’t wait for a routine screening. Talk to your doctor about your symptoms right away. They may recommend you have psychotherapy, or a combination of psychotherapy and antidepressants.

If you have symptoms of depression, talk to your doctor. They can evaluate you and offer you treatment or refer you to a mental health professional.

The type of treatment they recommend for you will depend on your symptoms and how severe they are. You may need one or more of the following:

  • Medication. Antidepressant medications (used alone or with psychotherapy) are effective for most people with depression. There are many types of antidepressants. You may have to try several kinds before you find the one that works best for you. You may need a combination of two. Or your doctor may also prescribe another type of medication to help your antidepressant work best, such as a mood stabilizer, antipsychotic, anxiety medication, or stimulant medication.
  • Psychotherapy. Talking to a mental health professional on a regular basis about your depression and other issues can help treat your symptoms. Methods include cognitive behavioral therapy (CBT), a common form of talk therapy.
  • Hospital or residential treatment. If your depression is bad enough that you’re having trouble taking care of yourself, or you may harm yourself or others, you may need psychiatric treatment in a hospital or residential facility.
  • Electroconvulsive therapy (ECT). In this treatment, electric currents are passed through your brain to help your neurotransmitters work better. Typically, you won’t have this therapy unless antidepressants aren’t working, or you can’t take them for other health reasons.
  • Transcranial magnetic stimulation (TMS). Your doctor typically suggests this only after antidepressants haven’t worked. This treatment uses a coil to send magnetic pulses through your brain to help stimulate nerve cells that regulate your mood.

Yes. Another treatment is transcranial magnetic stimulation (TMS). It involves using a noninvasive device that’s held above your head to create a magnetic field. It targets a specific part of your brain that can trigger your depression.

Vagus nerve stimulation (VNS) is another treatment option. A pacemaker-like device is surgically implanted under your collarbone to deliver regular impulses to your brain. 

A medication called ketamine may also be used for hard-to-treat depression. It is given through an infusion or as nasal spray.

Some lifestyle habits can help you manage your depression and lessen its symptoms. They include:

Getting regular exercise. Physical activity including aerobic exercise, tai chi, yoga, and weight training have been shown to increase your body’s production of endorphins, which are hormones that improve your mood.

Studies show aerobic exercise such as walking and swimming can be as effective as an antidepressant in reducing depression. Those who continue to exercise are less likely to have their depression come back. 

Avoiding alcohol. While you may drink alcohol to relax, it can cause problems like depression and anxiety down the road. Alcohol is a depressant that can interfere with the neurotransmitters that control your mood.

Avoiding caffeine. It can worsen your anxiety by increasing your stress hormone cortisol.

Drinking water. Even mild dehydration can worsen your mood and increase your anxiety. Experts recommend men have 15 cups of water per day and women have 11. Of that, 80% should come from drinking water and 20% from the food you eat.

Taking care of yourself. Get enough sleep, set boundaries in your personal and professional life, eat a healthy diet, and practice stress-reduction techniques such as mindfulness. These can help you better cope with life’s challenges without becoming depressed.

In addition to these steps, ask your doctor about supplements, vitamins, or herbs that may help with any symptoms of depression you’re having.

All types of depression may not be preventable. But there are some things you can do to help avoid it or lessen symptoms. 

Research shows that if you’ve had depression before, you may be more likely to have it again. But once you’ve experienced it, you can help prevent another one by learning which lifestyle habits and treatments work best for you.

Some helpful tips include:

  • Don’t stop your treatments for depression.
  • Reduce your stress as much as possible.
  • Build strong relationships with others.

Depression carries a high risk of suicide. Warning signs include:

  • A sudden switch from sadness to extreme calmness, or appearing to be happy
  • Always talking or thinking about death
  • Clinical depression (deep sadness, loss of interest, trouble sleeping and eating) that gets worse
  • Taking risks that could lead to death, such as driving through red lights
  • Making comments about being hopeless, helpless, or worthless
  • Putting affairs in order, like tying up loose ends or changing a will
  • Saying things like "It would be better if I weren't here" or "I want out"
  • Talking about suicide
  • Visiting or calling close friends and loved ones

If your symptoms of depression are causing problems with your relationships, work, or family -- and there isn't a clear solution -- you should see a professional. Talking with them can help prevent things from getting worse, especially if your symptoms last.

Anybody thinking or talking about harming themselves should be taken seriously. It’s time for immediate action.

If you’re thinking about hurting yourself or attempting suicide, or if you know someone who’s in danger of suicide, call 911 or your local emergency number right away.

And if you’re having suicidal thoughts:

  • Call or text the Suicide and Crisis Lifeline at 988, anytime day or night.
  • Call your doctor or mental health professional.
  • Reach out to a close friend or loved one.
  • Contact a minister, spiritual leader, or someone else in your faith community.