Consciousness › Disturbance of Consciousness › Restriction of Consciousness

Twilight State

A twilight state is a specific, well-described pattern combining a restriction of morbidly changed consciousness, a break in the continuity of consciousness, and relatively well-ordered behaviour throughout. Kept strictly to these defining criteria, the most common cause is epilepsy, though the term has also been applied more loosely to a range of other conditions involving a real or apparent restriction of consciousness, including simple, hallucinatory, perplexed, excited, expansive, psychomotor, and orientated varieties.

This has traditionally been characterised, where organic in origin, by a sudden onset and end, a variable duration, and the occurrence of unexpected violent or emotional behaviours, with the ICD-10 classifying twilight states under either dissociative (conversion) disorders or, when organic criteria are met, organic mental disorders.

Recognition features

• A restriction of morbidly changed consciousness combined with a break in the continuity of consciousness
• Behaviour remains relatively well-ordered throughout the episode, despite the underlying disturbance
• When organic in origin, sudden onset and end, variable duration, and the possibility of unexpected violent or emotional behaviour during the episode
• The strictest use of the term applies to epilepsy-related presentations, though it has also been applied more loosely across several other described varieties

Eliciting it at interview

• Take a careful history of onset and offset, since a sudden, well-demarcated beginning and end is characteristic of an organic, particularly epileptic, twilight state
• Ask about behaviour during the episode from witnesses, since well-ordered but ultimately non-purposeful behaviour, sometimes with unexpected violent or emotional outbursts, is a recognised pattern
• Consider EEG and appropriate neurological assessment where an epileptic twilight state is suspected, given its status as the classic, strictly defined cause

Distinguishing features

• Differs from restriction of consciousness more broadly in requiring the additional, specific feature of a break in the continuity of consciousness, rather than simply a narrowing of awareness
• Differs from a hysterical (dissociative) twilight state, a specific variety in which unconscious motives, rather than an organic process such as epilepsy, drive the restriction of consciousness
• Its classification under either dissociative (conversion) disorders or organic mental disorders in ICD-10 depends on whether organic criteria are met, so careful assessment of underlying cause is essential

Common misconceptions

• That a twilight state necessarily involves obviously disordered or dangerous behaviour; behaviour is often well-ordered and can appear largely unremarkable, aside from occasional unexpected violent or emotional episodes
• That the term twilight state refers to a single, uniform clinical picture; the book notes it has been applied loosely to several distinct described varieties beyond the strict, epilepsy-associated definition

Related phenomena

Restriction of Consciousness · Hysterical Twilight State

Practice this

A man with epilepsy is witnessed to wander from his workplace, behaving in a relatively well-ordered way throughout, before returning to full awareness twenty minutes later with no memory of the episode at all — a clean break rather than a gradual return. What is this presentation called? · A woman describes feeling gradually more and more absorbed in vivid, dream-like scenes over several hours, with the boundary between her ordinary awareness and the altered state impossible for her to pinpoint. Before revealing the answer: is this a twilight state? · A patient has had an episode matching the pattern of a twilight state. Before revealing the answer, decide what distinguishes a hysterical (dissociative) twilight state from an organic one. · A patient has had an episode of narrowed awareness with relatively organised behaviour. Before revealing the answer, decide what distinguishes a twilight state from restriction of consciousness more broadly. · A patient describes a period of 'losing time' and you want to establish whether this was a twilight state. Before revealing the answer, decide what you would ask about. · Explain why a twilight state can be clinically easy to miss, despite involving a genuine disturbance of consciousness.

Illustration

A 38-year-old man with a known seizure disorder is later found to have spent almost an hour wandering through a shopping centre, calmly browsing items and even purchasing a coffee, with no memory whatsoever of any of it afterward, the episode beginning and ending abruptly according to witnesses who noticed nothing obviously unusual about his behaviour at the time.

References

• Casey, P. & Kelly, B. (2019). Fish's Clinical Psychopathology, 4th ed. Ch. 9, 'Disorders of Consciousness'.