Psychosis
A state of losing contact with shared reality, with hallucinations (usually voices), delusions (fixed false beliefs such as persecution, special significance or being controlled) and disorganised thinking or speech. It can occur in schizophrenia, bipolar disorder, severe depression, with drugs, sleep deprivation or medical illness.
What drives it
A disturbance in how the brain assigns significance to perceptions and thoughts: ordinary events start to feel meaningful, personal or threatening, and the mind builds an explanation that then feels certain. Stress, cannabis and sleep loss are common precipitants.
How it shows
Work
Early signs are often subtle: withdrawal, falling performance, odd or tangential emails, suspicion that colleagues are plotting or monitoring them, references to hidden messages, laughing or reacting to things no one else hears, neglect of grooming. Strange certainty about a theory that does not add up.
Relationships
Sleep disturbance, increasing isolation, accusations of betrayal, unusual religious or technological preoccupations, flat emotional expression, speech that is hard to follow. Family usually notice a change from the person they knew over weeks or months.
Self
Things start to seem connected or meant for you; you feel watched; thoughts may seem loud or not quite your own. From inside, the new explanations feel obvious, which is why insight is often lost.
What tells it apart
Paranoid personality: Paranoid personality is lifelong suspicion and grievance-holding within the bounds of plausibility; psychosis is a change from baseline with implausible beliefs (implants, broadcasts, conspiracies) and often hallucinations.
Schizotypal personality: Schizotypal people hold odd beliefs and magical ideas with some flexibility and stable functioning; in psychosis beliefs become fixed and unshakeable and functioning drops.
Dissociation (including depersonalisation and derealisation): In dissociation the person feels unreal or detached but knows the world is real ('as if'); in psychosis they believe the unusual experience is literally true.
A test
Watch for a change from baseline over weeks (withdrawal, suspicion, odd beliefs held with certainty, sleep loss), avoid arguing with the beliefs, and seek urgent assessment through a GP, early intervention service or emergency care, because early treatment strongly improves outcome.
How strong the research is
strong
Where it comes from
Term coined by Ernst von Feuchtersleben, 1845; Emil Kraepelin's dementia praecox, 1899; Eugen Bleuler's 'schizophrenia', 1911; Kurt Schneider's first-rank symptoms, 1939 (English translation 1959); at-risk mental state by Alison Yung and Patrick McGorry, 1990s