A 63-year-old Caucasian man reported 1 year of sleep disturbance. He described waking repeatedly from sleep with feeling light-headed upon sitting up. He would then gasp for air, move his head from side to side, lose consciousness for a few seconds and recover immediately without confusion. He also had similar episodes during the daytime, although less frequently. He had frequently felt light-headed on standing for some time. He had been previously well apart from some situational vasovagal syncope as a teenager. He had a normal birth and early life, with normal developmental milestones. On examination, there was a postural drop in blood pressure from 120/90 mm Hg (lying) to 100/70 mm Hg (standing) after 3 min. Neurological and cardiology examinations were otherwise normal.

Comment

The main differential diagnoses are syncope and epilepsy. While the episodes were stereotyped, suggesting epilepsy, other features—such as the consistent prodrome of preceding light-headedness and previous vasovagal episodes—might suggest autonomic dysregulation, possibly with sleep parasomnia or cardiac syncope.

Misdiagnosing blackouts can increase mortality and morbidity: there are several well-recognised clinical markers that can help to differentiate seizures from syncope.