Synergistic effect of sleep depth and seizures correlates with postictal heart rate.

Our objective was to determine the effect of sleep on heart rate following a recorded seizure. We prospectively acquired heart rate data in hospitalized epilepsy monitoring unit patients. We analyzed heart rate trends for multiple seizures (n = 101) in patients (n = 42) with electroencephalographically confirmed events. The patient's sleep state was scored for the 5 min preceding each seizure and correlated with the postictal nadir heart rate (PINHR). The depth of sleep during the 5 min before a seizure correlated (correlation coefficient [CC] = -.229, p < .05) with PINHR. This result was more significant and strengthened (CC = -.272, 95% confidence interval = -.392 to -.152, p < .001) when adjusted for covariates of age, generalized tonic-clonic seizures, and baseline heart rate. Sleep depth is an independent predictor of the change in heart rate following a seizure. Diminished heart rate following a seizure in the setting of sleep is likely secondary to non-rapid eye movement sleep's synergistic effect on parasympathetic tone.