Vigilance and circadian function in daytime and nocturnal epilepsy compared to controls

People with epilepsy often experience daytime vigilance problems and fatigue. This may be related to disturbed sleep due to nocturnal seizures.

To compare subjective and objective markers of vigilance and circadian function in adults with epilepsy with nocturnal seizures to those with daytime seizures and healthy controls and to identify determinants of impaired daytime vigilance in epilepsy in an explorative study.

We included 30 adults with epilepsy (15 with daytime seizures and 15 with nocturnal seizures), and 15 healthy controls. All participants filled out the Epworth sleepiness scale (ESS), fatigue severity scale (FSS), Pittsburgh sleep quality index (PSQI) and the Munich chronotype questionnaire (MCTQ). Each participant performed two trials of the sustained attention to response task (SART) as a measure of vigilance, and had a post-illumination pupil response (PIPR) assessment as a marker for the circadian function.

Both epilepsy groups reported more fatigue on the FSS than healthy controls (p < .001) and had higher SART error scores (p = .026). The poorer FSS and SART scores were most prominent among those with nocturnal seizures. The ESS, PSQI, MCTQ and the primary PIPR outcome did not differ between groups. Having nocturnal seizures (p = .010) and using more antiseizure medications (p = .004) were related to increased SART error scores.

Nocturnal epilepsy is associated with poorer vigilance, indicating lower quality of wake time. We could not relate this to circadian dysfunction. Further studies should focus on vigilance problems in people with nocturnal epilepsy and explore interventions to improve the quality of wake time.