Factors affecting the occurrence of high-frequency positive occipital sharp transients of sleep.

To elucidate possible factors affecting the incidence of high-frequency positive occipital sharp transients of sleep (H-POSTS) and to investigate whether H-POSTS are associated with any specific pathophysiological conditions, we visually inspected on consecutive routine diurnal EEGs (2705 records) using our criteria for identification of H-POSTS. H-POSTS were observed in 164 records (subject age: 7.9 to 83.2 years). The incidence of H-POSTS was lower in subjects with highly abnormal EEG findings. Female subjects had a significantly higher incidence of H-POSTS than males that could not be explained by other factors. Patients with either fainting or headache had a significantly higher incidence of H-POSTS and lower grade of EEG abnormality. The precise mechanism of the gender difference in the incidence of H-POSTS could not be determined. The occurrence of H-POSTS seemed to be associated with healthy sleep macrostructure, rather than with any specific pathophysiological phenomena.