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What Is Depression? Symptoms, Causes & Treatments

Kristin Hall, FNP

Reviewed by Kristin Hall, FNP

Written by Our Editorial Team

Published 07/16/2020

Updated 02/01/2022

Depression is a common mental illness that can affect the way you think, feel and behave. It’s a serious mood disorder that can have a negative impact on almost every aspect of your life, from your feelings to your hobbies, career and relationships.

More than anything else, depression can feel like a heavy, pervasive sadness that hangs over your daily life. You might have days where things are looking better and days where you're too depressed to get out of bed. Even finding relief for a moment can feel hopeless. 

The good news is that depression, even when severe, is treatable. By accessing help, you can overcome depression and enjoy a fulfilling, satisfying life once again.

Below, we’ve explained what depression is, as well as the symptoms you may experience when you’re depressed. We’ve also discussed the different factors that can either cause or contribute to depressive illness. 

Finally, we’ve discussed the treatment options that are available for depression, from medication to therapy, lifestyle changes and more. 

Depression is a common type of mental illness called a mood disorder. It can cause severe and persistent symptoms that have a noticeable negative effect on the way you think, feel and act on a daily basis. 

Like many other mental disorders, depression is very common. According to data from the 2019 National Survey on Drug Use and Health, an estimated 19.4 million US adults experienced one or more depressive episodes in 2019. 

Depression is more than just feeling sad. When depression occurs, it can have a serious impact on your life. According to the CDC, 80 percent of adults with depression report facing difficulties with social, work and home activities because of the condition.

Although depression is often thought of as a single condition, there are many different forms of depression that can affect a person’s moods, thoughts and behavior. 

Common forms of depression include:

  • Major depressive disorder. Also referred to as clinical depression, this is a common form of depression that typically involves severe, persistent symptoms that affect how you feel, think and behave on a daily basis.To be diagnosed with major depressive disorder, you’ll typically need to experience a range of depressive symptoms that continue for two weeks or longer.

  • Persistent depressive disorder. This form of depression, which is also referred to as dysthymia, is a long-lasting form of depression involving symptoms that persist for two years or longer.

  • Seasonal affective disorder. This is a form of depression that occurs over the winter months, before gradually fading away as the seasons change. It may affect people in cold areas with limited natural sunlight during the winter.

  • Atypical depression. This form of depression involves many of the symptoms of major depression combined with mood reactivity (the ability to respond to positive events). It’s often referred to as depression with atypical features.

  • Bipolar disorder. This mood disorder involves depressed episodes in combination with euphoric, or “manic” periods. Although it’s technically not a form of depression, it shares many common symptoms with depressive illnesses.

  • Postpartum depression. This form of depression develops in women during pregnancy or after giving birth. It’s more severe than the “baby blues” that often develop after giving birth and can have a significant impact on a person’s wellbeing.

  • Psychotic depression. This form of depression involves severe depression and some psychotic symptoms, such as delusions or hallucinations.

Our guide to the types of depression provides more information about the forms of depression listed above, as well as their unique symptoms, risk factors and treatment options. 

Depression can involve a range of symptoms that affect your moods, feelings, thoughts and the ways you behave. For many people, it also involves physical symptoms. These symptoms tend to be persistent and range in their severity from moderate to overwhelming. 

Common depression symptoms include:

  • A persistent, pervasive feeling of sadness and/or emptiness

  • The belief that things are hopeless and difficult to improve

  • Frequent feelings of irritability and annoyance

  • A negative, pessimistic or helpless outlook

  • Feeling as if you’re guilty or worthless

  • Fatigue and generally decreased levels of energy 

  • A feeling of restlessness and difficulty keeping yourself still

  • Difficulty falling asleep, staying asleep or waking up too early

  • Oversleeping and finding it difficult to get out of bed in the morning

  • Reduced speech and/or movement speed

  • A loss of interest in hobbies and other activities you used to enjoy

  • Cramps, pains, aches, headaches and other feelings of discomfort

  • Digestive problems that don’t improve with treatment

  • Changes in your appetite with weight gain or weight loss

  • Suicidal thoughts and/or suicide attempts

The precise symptoms of depression vary from person to person. Some people with depression develop many severe symptoms, while others may only experience a few symptoms that vary in severity over time.

In order to be diagnosed with major depressive disorder, you’ll need to have several symptoms in addition to a depressed mood. These symptoms will need to affect you for most of the day on a daily or near-daily basis for a period of at least two weeks. 

Our guide to the symptoms of depression goes into more information about how you might feel, think and behave if you’re depressed. 

There’s no single direct cause of depression -- it’s a complex mental disorder. Current research suggests that a range of factors all play a role in the development of depression, including your genes, environment and psychological health.

Genetic Factors

Along with a complex and not yet entirely understood array of social and environmental factors, there are dozens of different genes that can potentially play a role in your moods, including some that may affect your risk of developing depression. Certain genes, such as those that control your stress response, might be at least partly responsible for some aspects of depressive illnesses.

Life Events

Sometimes, stressful or difficult life events can play a role in the development of depression. If a difficult event happens that affects you, or if you’re going through a stressful period in your life, it could act as a trigger for depression.

Life events that may cause or contribute to depression could include losing your job, developing a sudden, unexpected medical condition, ending a major relationship or dealing with the death of a loved one.

Medical Conditions

Depression often co-occurs with medical conditions. You may develop depression as a result of an illness such as cancer, diabetes, heart disease or Parkinson's disease, or from a medication used to treat one of these conditions.

Other Causes of Depression

Other factors, such as chronic stress, loneliness and substance abuse, can all play a part in the development of depression. Our guide to the causes of depression goes into more detail about the specific factors that might cause you to become depressed. You may also be curious if there are any drugs that cause depression, which we've also covered.

Anyone can potentially become depressed. However, certain people may have a higher risk of developing depression than others. Understanding what can increase your risk of depression can help you to recognize depression when it develops and seek treatment early.  

You may have a higher risk of developing depression if you:

  • Have a family history of depression. Depression and other mental illnesses have a genetic component, meaning you may have a higher risk if one or several of your family members is depressed or has previously suffered from depression.

  • Have experienced a sudden change in life. Sudden changes, such as relocating to a new city, losing your job or suffering a personal setback in life, may increase your risk of becoming depressed.

  • Have financial issues. Some scientific research, including studies of students, suggests that financial difficulties are linked with the development of depression and other forms of mental illness.

  • Have a medical condition. Conditions associated with depression include degenerative neurological conditions such as Parkinson’s disease and multiple sclerosis, HIV, cancer, stroke, endocrine disorders, immune system diseases and erectile dysfunction (ED).

  • Use certain types of medication. Some medications used to treat hypertension (high blood pressure) and other conditions may increase your risk of developing depression and/or other forms of mental illness.

Depression, even when it’s severe, is treatable. Most of the time, depression can be treated with the use of medications called antidepressants, psychotherapy and changes to your daily life and habits.

Since everyone is different, there’s no “perfect” way to treat depression for everyone. If you feel depressed and want to get help, it’s important to talk to a mental health provider about the steps that you can take to recover. 


Depression is treated using antidepressant medications. These medications work by increasing the levels of naturally-occurring chemicals, called neurotransmitters, that control certain aspects of your moods and feelings.

There are several different types of antidepressants. One of the more popular is a class of drugs called selective serotonin reuptake inhibitors, or SSRIs.

SSRIs work by increasing the amount of serotonin in the brain. Serotonin regulates your sleep cycle, mood, happiness and anxiety. By increasing your serotonin levels, SSRIs can make the symptoms of depression less severe.

SSRIs are typically used as first-line treatments for depression. Other types of antidepressants include serotonin-norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs).

Antidepressants can take several weeks to start working, and they may improve your sleep and appetite before they cause you to feel better. It’s important to continue using your medication, even if you don’t notice any immediate improvements.

We offer several FDA-approved antidepressants online, following a consultation with a licensed provider via our online psychiatry service


Depression often improves with psychotherapy, or talk therapy. Your mental health provider may suggest taking part in therapy alone, or as part of a combination treatment with medication such as antidepressants. 

Several forms of therapy can help to treat depression, including interpersonal therapy (IPT) and cognitive-behavioral therapy (CBT). 

Our guide to therapy for depression provides more information about how therapy can help you deal with the symptoms of depression and work towards recovery. 

Electroconvulsive Therapy (ECT)

If medication and conventional forms of therapy aren’t effective, your mental health professional may recommend electroconvulsive therapy.

This type of therapy involves the use of small electric currents to stimulate the areas of the brain affected by depression. It’s often an effective treatment for people affected by severe depression who don’t respond to other forms of treatment.

Habits and Lifestyle Changes

In addition to professional treatment, making certain changes to your habits and lifestyle is often beneficial for treating depression. Try to:

  • Keep yourself active and exercise regularly (Yes, there is a link between exercise and depression)

  • Eat a healthy, balanced diet

  • Maintain healthy sleep habits

  • Spend time with your friends and family

  • Set clear, achievable goals for your recovery

  • Focus on making gradual progress

Our list of self-help strategies for depression shares other lifestyle changes and habits that you can use to improve your results from depression treatment. Or maybe you're curious about an alternative treatment such as hypnosis for depression.

Depression is a serious mental illness that’s much more than just “feeling down.” When you’re affected by depression, your symptoms can feel overwhelming and interfere with almost every aspect of your life. 

Even when severe, depression is treatable. The earlier you reach out for help and start to treat your depression, the more likely it is that you’ll achieve good results.

If you’re feeling depressed, you can use our range of online mental health services to connect with a professional and access the help you need. 

8 Sources

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  6. Richardson, T., Elliott, P., Roberts, R. & Jansen, M. (2017). A Longitudinal Study of Financial Difficulties and Mental Health in a National Sample of British Undergraduate Students. Community Mental Health Journal. 53, 344-352. Retrieved from
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  8. What is Serotonin? (2018, December). Retrieved from
Editorial Standards

Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references. See a mistake? Let us know at [email protected]!

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.

Kristin Hall, FNP

Kristin Hall is a board-certified Family Nurse Practitioner with decades of experience in clinical practice and leadership. 

She has an extensive background in Family Medicine as both a front-line healthcare provider and clinical leader through her work as a primary care provider, retail health clinician and as Principal Investigator with the NIH

Certified through the American Nurses Credentialing Center, she brings her expertise in Family Medicine into your home by helping people improve their health and actively participate in their own healthcare. 

Kristin is a St. Louis native and earned her master’s degree in Nursing from St. Louis University, and is also a member of the American Academy of Nurse Practitioners. You can find Kristin on LinkedIn for more information.

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