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Depression is a low mood that lasts for a significant amount of time. The severity of depression can vary: a mild depression might not stop you from doing your normal activities, although it can make them harder to do and things might not feel worthwhile; when depression is more severe it can leave you feeling suicidal and unable to function normally. Depression can have many causes – for some people there are clear triggers, but others can find it difficult to understand why they are depressed. It is thought that between 3 and 7 people out of every 100 will experience depression every year [1, 2]. Fortunately, there are many effective psychological and medical treatments for depression.

What is it like to have depression?

Tanya’s depression followed a breakup

Tanya was 36 when she came to treatment. Her relationship with Phil had broken up after seven years. This was difficult for her as she had moved cities to be with him. Since the breakup she had been feeling devastated and worthless. She used to be an active person but she struggled to motivate herself to work, stayed in when she could, and had taken a lot of time off sick. She wasn’t doing anything she enjoyed, and was worried her manager would get rid of her. Tanya said that she would often wake during the night and find herself going over all the things that had gone wrong in her life. She felt completely hopeless about her prospects for the future and said that she often had thoughts like “Now I will never have children”, “My mother was right, I’ll never make a success of my life”.

Aspects of treatment that Tanya found helpful

Tanya found it a struggle to commit to engaging with a psychological therapy, but she found her counsellor sensitive and caring and she began to open up. The parts of therapy that she found most helpful were understanding the links between her thoughts, actions, and feelings, and the effect of her rumination on her mood. Her counsellor recommended behavioral activation as an initial treatment and although she found it difficult, it did make a difference to her mood. Later in therapy Tanya made some important links between some of her early experiences – particularly the way she had been treated by her mother when she was a child – and the harsh way that she spoke to herself now. She learned to catch and challenge some of her negative and critical ways of thinking, and she began to see herself in a new light.

What is depression?

Depression is a low mood that lasts for a significant amount of time. Some of the signs and symptoms that you may experience if you are depressed include:

  • Feeling depressed or down for most of the day, nearly every day.
  • Less interest in things that you previously found interesting.
  • Feeling fatigued or a loss of energy.
  • Sleeping too much or too little.
  • Feeling worthless, being hard on yourself, or feeling guilty.
  • Feeling unable to concentrate or feeling indecisive.
  • Recurrent thoughts of death or suicide, suicidal behavior, or self-harm.
  • Eating too little or too much.
  • Feeling so fidgety that you can’t sit still or moving and speaking more slowly than normal.

Some people have a one-off episode and recover, other people experience many episodes of depression throughout their life. If you have struggled with depression before then further episodes can be more easily triggered. We can separate the effects of depression into thoughts, feelings, and behaviors:

How you might think How you might feel How you might act
  • Dwelling on past & current mistakes & failures
  • Self-critical thoughts
  • Thoughts that you are worthless
  • Thoughts that things don’t matter or that life has no meaning
  • Hopeless thoughts that things are never going to get better
  • Thoughts about ending your life
  • Down, upset, or tearful
  • Restless or agitated
  • Empty and numb
  • Tired and low on energy
  • Unable to concentrate
  • Indecisive
  • Suicidal
  • Lonely and ‘cut off’
  • Stop doing things that you used to enjoy
  • Avoiding things that you used to do
  • Eating more or less than is normal for you
  • Sleeping more or less than is normal for you

What causes depression?

There is no single cause for depression. Some of the factors that make it more likely that you will experience depression include [3]:

  • Critical incidents which kick-start the depression. These can include losses (e.g. bereavement, the end of a relationship, losing a job, children leaving home), transitions (e.g. leaving home, retiring, having a baby), physical illness, loneliness, or any other significant or stressful events.
  • A tendency to think negatively. More than just a pessimistic attitude, this is an automatic ‘habit’ of seeing the worst in things (“glass half-empty thinking”).
  • Early experiences which made you vulnerable to depression. These can include abuse, neglect, bullying, poor relationships, living with a parent who was depressed or had emotional difficulties, or losses.
  • Holding unhelpful beliefs and assumptionsFor example, “unless I succeed in all areas I am worthless”, “I should be happy all the time”, “I can’t be happy unless I am loved”. These are often closely related to our early experiences (see above).
  • Genetic factors. There may be genes which predispose people to developing emotional problems in general, but no specific genes which predispose someone to developing depression.

What keeps depression going?

Cognitive behavioral therapy (CBT) is always very interested in what keeps a problem going. This is because if we can work out what keeps a problem going we can treat it by interrupting this maintenance cycle. CBT therapists and researchers have proposed three main theories to understand what keeps depression going:

  • Behavioral model
  • Cognitive model
  • Cognitive behavioral model

Behavioral theory of depression

The behavioral theory of depression notes that there is a strong relationship between what you do and how you feel. When you are feeling good you are more likely to spend time with people whose company you enjoy, take part in activities that make you feel good, and take on new tasks and adventures that challenge you as a person. All of this activity has positive feedback effects:

  • Doing things you enjoy gives you feelings of pleasure.
  • Challenging yourself means that you have a chance to grow and develop. It gives you a sense of mastery and achievement.
  • Having positive relationships with other people makes you feel connected and valued.

The reverse is true too. When you are depressed you are likely to do less overall and so you have fewer opportunities to feel pleasure, mastery, achievement, and connection – the things you need to feel good. It is easy to fall into a trap:

Behavioral theory of depression

Figure 1: According to the behavioral model of a lack of rewarding activity leads to depression, which leads to further inactivity.

When you are depressed it can be as though your motivation works in reverse – you need to get active before you feel good again. An effective way of breaking this vicious cycle of depression is to increase your level of activity even if you don’t feel like it to begin with. This approach is called Behavioral Activation (BA) and it is an evidence-based treatment for depression.

Cognitive theory of depression

Aaron Beck’s cognitive theory of depression [4] had the insight that the way you think affects the way you feel. When we are happy our thoughts tend to be optimistic – we can see the bright side even when stressful things happen. But depressed people’s thinking often changes in important ways: when we are feeling depressed our thoughts can become quite extreme and quite negative; and depressed people are prone to interpret situations in negative ways which leaves them feeling bad. Depressed thoughts can be about ourselves, the world or other people, and our future.

The way you interpret situations drives how you feel about them.

Cognitive theory of depression

Figure 2: According to the cognitive model depression is underpinned by patterns of negatively biased thinking.

Cognitive therapy for depression pays close attention to your thinking patterns. A cognitive therapist will help you to identify unhelpful ways in which you are thinking. They will help you to practice different ways of thinking, one of which might be to help you to interpret things in a more balanced way.

Cognitive-behavioral theory of depression

The cognitive-behavioral theory of depression incorporates both the cognitive and behavioral theories. It says that what you think and do affects the way you feel. Your depression might be maintained by a mixture of interpreting things in unhelpful ways and acting in ways that are self-defeating.

Figure 3: The cognitive behavioral model understands depression to be the result of patterns of negative thinking and acting.

Cognitive behavioral therapy for depression will explore your patterns of thinking and acting in order to understand what is keeping you depressed. A CBT therapist will use treatment techniques that help you to change your unhelpful behavioral (doing) and cognitive (thinking) habits.

Treatments for depression


Effective psychological treatments for depression include: behavioral activation (BA), cognitive behavioral therapy (CBT), interpersonal therapy (IPT), short-term psychodynamic therapy, and acceptance and commitment therapy (ACT). Mindfulness based cognitive therapy (MBCT) has been shown to prevent relapse in people who have recovered from depression, or who have had three or more episodes of depression [5].


The National Institute for Health and Care Excellence (NICE) recommends SSRI-type antidepressant medication for depression. If an individual does not respond to SSRIs other drug classes including tricyclic antidepressants can be considered, and antidepressant treatment can be augmented with lithium or antipsychotic drugs [5].

How can I overcome my depression?

There are lots of things that you can do for yourself that can help you to overcome depression. Self-help treatments for depression include:

Activating yourself with behavioral activation

Behavioral activation (BA) is about making your life meaningful and pleasurable again. To do BA effectively you will need to follow these steps:

You can learn more about behavioral activation in our Psychology Tools guide to behavioral activation.

Changing the way you think with cognitive restructuring

The goal of CBT is not to ‘think happy thoughts’ but is instead to think accurately, and in a way that is balanced, realistic, and helpful. Anyone’s thinking can become biased, but it is within our power to change the way we think. CBT teaches a number of steps for working with your thoughts:

You can learn more about identifying and challenging your negative thoughts in our Psychology Tools Guide to Cognitive Restructuring.

Mindfulness for preventing relapse

Mindfulness is a traditional Buddhist meditation practice. Since the 1980’s components of mindfulness practice have been increasingly adopted by psychological therapists in a secular way. It is now used as a way of helping people experience a different kind of relationship with their thoughts and minds. Mindfulness is used very widely but one area for which there is a particularly strong evidence base is the use of mindfulness to prevent relapse in depression – especially if you have experienced three or more depressive episodes. Mindfulness-based cognitive therapy (MBCT) combines mindfulness training with teaching of psychological skills to combat relapse in people with a history of depression.


[1] Stansfeld, S., Clark, C., Bebbington, P., King, M., Jenkins, R., & Hinchliffe, S. (2016). Chapter 2: Common mental disorders. In S. McManus, P. Bebbington, R. Jenkins, & T. Brugha (Eds.), Mental health and wellbeing in England: Adult Psychiatric Morbidity Survey 2014. Leeds: NHS Digital.

[2] Kessler, R. C., Chiu, W. T., Demler, O., & Walters, E. E. (2005). Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication. Archives of General Psychiatry62(6), 617-627.

[3] Beck, A. T., Bredemeier, K. (2016). A unified model of depression: integrating clinical, cognitive, biological, and evolutionary perspectives. Clinical Psychological Science, 4(4), 596-619.

[4] Beck, A. T., Rush, A. J., Shaw, B. F., Emery, G. (1979). Cognitive Therapy of Depression. New York: Guilford press.

[5] National Institute For Health And Care Excellence (2009). Depression in adults: recognition and management. Retrieved from:

About this article

This article was written by Dr Matthew Whalley and Dr Hardeep Kaur, both clinical psychologists. It was reviewed by Dr Hardeep Kaur and Dr Matthew Whalley on 2019-09-12.