DISORDER GUIDES · GUIDE 01
Major depressive disorder
Major depressive disorder is more than a bad week or ordinary grief. It is a sustained state — at least two weeks — in which mood, energy, interest, sleep, appetite, and thinking shift together and begin to interfere with work, relationships, and self-care. It is common, it is not a character flaw, and it is treatable.
These guides describe patterns clinicians look for — not a diagnosis of any reader. A label is a map, not the person: two people with the same diagnosis can look very different, and only a clinician who knows your history can say what a pattern means. If you recognize yourself in one of these guides, treat that as a reason to start a conversation with a professional, not as a conclusion.
EVIDENCE REVIEW
OCTOBER 18, 2026
Common signs
- Persistent low, empty, or irritable mood most of the day, most days
- Loss of interest or pleasure in things that used to matter (anhedonia)
- Sleep change — insomnia, or sleeping far more than usual
- Appetite or weight change, up or down
- Fatigue and slowed movement or speech — or physical restlessness
- Trouble concentrating, remembering, or deciding
- Feelings of worthlessness or excessive guilt
- Recurrent thoughts of death or suicide
How it's diagnosed
A clinician listens for the pattern over time — at least two weeks of symptoms that represent a change and cause real impairment — and rules out medical causes such as thyroid disease, sleep apnea, vitamin deficiencies, and medication or substance effects, sometimes with basic labs. Severity is judged by intensity and function, not by how well someone can hide it. Screening tools like the PHQ-9 can support the conversation; they don't replace it.
How it's treated
Psychotherapy is a first-line treatment — cognitive behavioral therapy, interpersonal therapy, and behavioral activation have strong evidence. Antidepressant medications (SSRIs, SNRIs, and other classes, covered in the medication guides) are commonly used, especially for moderate to severe depression, and the combination of therapy and medication often works better than either alone. For severe or treatment-resistant depression, options such as TMS, esketamine, or ECT may be considered with a specialist.
When to seek help promptly
Seek help the same day if depression is deepening quickly, you cannot get out of bed or care for yourself or your children, or you stop eating and drinking. If you are having thoughts of suicide — especially with a plan or intent — treat it as an emergency: in the US, call or text 988, the Suicide and Crisis Lifeline, any time, or go to an emergency department.
