Clinical data are reported for 13 patients who were referred with recurrent loss of consciousness at night interrupting their sleep. Most of the patients were women (10 of 13) with a mean age of 45 years (range 21-72 years). The histories were more consistent with vasovagal syncope than with epilepsy. This was supported by electroencephalographic and tilt test results. More polysomnographic monitoring data are required to confirm the diagnosis of vasovagal syncope interrupting sleep. This will be difficult because, although the condition may not be rare, the episodes are usually sporadic.