Depression: Symptoms, Causes and Evidence-Based Treatment
Depression is a common mental health condition that brings a persistent low mood or a loss of interest in things you usually enjoy. It lasts for weeks or months and affects your thoughts, your body and your daily life. Effective depression treatment is available, and NICE recommends several talking therapies alongside medication.
What is depression?
Depression is more than feeling sad or fed up for a few days. Most of us have low spells that lift within a week or two without getting in the way of life too much. With depression, the feelings stay for weeks or months and are strong enough to affect your work, relationships and family life.
It's more common than many people realise. In England's Adult Psychiatric Morbidity Survey, 3.8% of adults had a depressive episode in the week they were assessed (2023/4). Depression and anxiety often appear together, and our article on why anxiety can look different in men explores one side of that overlap.
UK doctors describe depression as less severe (previously mild) or more severe (moderate or severe), depending on your symptoms, how long they last and their impact on daily life. Clinicians also use classification systems such as ICD-11.
Depression can change how you feel, how your body works and how you live day to day. You're unlikely to have every symptom listed here.
How you might feel
a continuous low mood or sadness
hopeless, helpless or tearful
low in self-esteem or weighed down by guilt
irritable and less tolerant of other people
unmotivated, with little interest or enjoyment in life
anxious or worried
unable to make decisions
having thoughts of suicide or of harming yourself
Signs and symptoms of depression
Changes in your body
moving or speaking more slowly than usual
changes in appetite or weight
unexplained aches and pains
a lack of energy
a low sex drive
disturbed sleep, such as struggling to fall asleep or waking very early
Changes in your daily life
seeing friends less and avoiding social activities
letting hobbies and interests slip
difficulties at home, at work or in family life
Depression often comes on gradually, so a friend or family member may notice the change before you do. If thoughts of suicide or self-harm are part of your experience, please use the urgent support details further down this page.
What causes depression?
There's no single cause of depression. For most people several things combine, and sometimes it develops with no obvious trigger at all. None of this means you brought it on yourself.
Things that can raise your risk include:
stressful life events, such as bereavement, divorce, illness, redundancy or money worries
personality traits, such as low self-esteem or being very self-critical
a family history of depression, which raises the risk without making it inevitable
loneliness, or becoming cut off from friends and family
drinking more alcohol or using drugs to cope
a long-term or serious physical illness, a severe head injury or an underactive thyroid
pregnancy, having a baby and the menopause
These factors can feed each other in what the NHS calls a "downward spiral": a hard event leads you to withdraw and drink more, which deepens the low mood. If your low mood began during pregnancy or after having a baby, our perinatal mental health support is designed for this stage of life.
How is depression diagnosed?
In the UK, depression is usually diagnosed by a GP. There's no physical test for it, though your GP may arrange blood tests to rule out conditions with similar symptoms, such as an underactive thyroid.
The assessment is mainly a conversation about how your mood affects daily life, your health history, recent stresses and whether you've had thoughts of suicide or self-harm. A short questionnaire such as the PHQ-9 is often used to gauge severity, which shapes the treatment you're offered.
The NHS advises seeing a GP if you've had symptoms for most of the day, every day, for more than two weeks. NHS talking therapies can involve waits of several weeks or months. A private assessment with a Clinical Psychologist is usually quicker.
Contact our team via email to book, or learn more about our comprehensive assessments for a range of mental health conditions.
Depression treatment: what NICE recommends
NICE guideline NG222, Depression in adults: treatment and management (2022), sets out the treatments recommended in England. Your clinician should agree a choice with you based on your needs and preferences, and you have the right to decline treatment.
Treatment for less severe depression
NICE recommends starting with the least intrusive option, which is often guided self-help, though group and individual therapies are also first-line options. NICE advises against routinely offering antidepressants as a first treatment for less severe depression, unless that's your preference.
Treatment for more severe depression
The first option NICE lists is individual CBT combined with an antidepressant. Therapy alone, antidepressants alone and the other approaches below are also first-line options, so medication and therapy aren't either/or.
| Therapy | What it focuses on | Typical course | May suit you if |
|---|---|---|---|
| Cognitive behavioural therapy (CBT) | How thoughts, beliefs, feelings and behaviour interact, with practical coping skills | Usually 8 sessions | You notice negative thoughts or unhelpful patterns you want to change |
| Behavioural activation | The link between what you do and how you feel, and reducing avoidance | Usually 8 sessions | Depression has led you to withdraw, do less, or followed a change in routine |
| Interpersonal psychotherapy (IPT) | How relationships and life changes connect to your mood | Usually 8 to 16 sessions | Your depression is tied to relationship difficulties, loss or a change of role |
| Counselling for depression | Exploring emotions and finding meaning, with empathic listening | Usually 8 sessions | Relationship, work or social problems are contributing |
| Short-term psychodynamic psychotherapy | Difficult feelings in close relationships and patterns that repeat | Usually 8 to 16 sessions | Long-standing relationship difficulties feed into how you feel |
| Guided self-help | Structured CBT or behavioural activation materials, with practitioner support | Usually 6 to 8 sessions | You're self-motivated and want flexibility around other commitments |
NICE notes that more sessions may be needed when depression comes with other mental or physical health problems or complex social needs.
Antidepressant medication
Antidepressants are prescribed by a GP or psychiatrist rather than a psychologist. SSRIs are the type most often offered first, and NICE says their benefits should be felt within four weeks. Some people find antidepressants hard to stop later, so agree any change with your prescriber. If hopelessness or suicidal thoughts start or worsen after starting an antidepressant, contact a GP straight away.
Therapy for depression at Regal Private Therapy Practice
We support adults with depression through our adult therapy service, using approaches recommended in NICE guidance, including individual CBT and behavioural activation.
Depression support is led by Simran Sutaria, a High Intensity CBT Therapist whose practice centres on anxiety and depression, and Dr Bradley Powell, a Chartered Clinical Psychologist and accredited CBT therapist registered with the HCPC.
You start with a 50 to 60 minute assessment, in person in London or online anywhere in the UK, and agree a personalised treatment plan together. We also support young people through our child and adolescent therapy service.
Get in touch with our team to talk through what's been happening.
If you need urgent support
If you are struggling to cope or worried about your safety, help is available now. Call 111 and select the mental health option, or contact your GP. Samaritans are available 24 hours a day on 116 123. In an emergency, call 999 or go to your nearest A&E.
If you are eating very little, or a child is, speak to a GP. This can affect physical health and should be looked at properly.
Frequently asked questions about depression
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Low mood usually lifts within a week or two and doesn't stop you getting on with life. Depression lasts longer, for weeks or months, and affects your work, relationships and routine. The NHS suggests seeing a GP if you've felt low for most of the day, every day, for more than two weeks.
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There's no fixed timeline. Depression typically lasts weeks or months rather than days, and its course varies from person to person. NICE recommends reviewing how well treatment is working two to four weeks after it starts, and most therapy courses run for around 6 to 16 sessions.
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Only a professional assessment can confirm it. Common signs include a persistent low mood, losing interest in things you used to enjoy, poor sleep and low energy. If you recognise several symptoms on this page, most of the day, nearly every day, for over two weeks, it's worth speaking to your GP or a Clinical Psychologist.
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Let them know you're there and that asking for help is okay, without pressuring them. You can't make someone get treatment, but gently encouraging them, staying in touch and still doing ordinary things together can make a difference. Look after your own wellbeing too. If they're at immediate risk, call 999.
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References
National Institute for Health and Care Excellence (2022). Depression in adults: treatment and management (NG222)
NHS England (2025). Adult Psychiatric Morbidity Survey: Survey of Mental Health and Wellbeing, England, 2023/4, Chapter 1
Royal College of Psychiatrists. Depression