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?

This is a twilight state: a restriction of morbidly changed consciousness combined with a break in the continuity of consciousness, with behaviour remaining relatively well-ordered throughout, and — in its organic, epilepsy-related form — sudden onset and end, exactly as described here. It is not restriction of consciousness alone, since that describes a narrowing of awareness without necessarily the additional, specific feature of a break in continuity that defines a twilight state. It is not a dream-like change of consciousness, which is characterised by florid, complex hallucinatory experience rather than well-ordered wandering behaviour. And it is not lowering of consciousness (torpor), which involves uniformly slowed and benumbed behaviour, not the organised activity described here.