Progressive change in sleep over multiple nights of intracranial EEG monitoring

Objective: We evaluated changes to sleep structure during continuous intracranial EEG (icEEG) monitoring of epilepsy patients undergoing localization of the seizure onset area.

Methods: We studied 28 adult epilepsy patients who underwent icEEG monitoring for a median of 12 nights. We used a metric calculated from relative delta power (RDP) to evaluate the emergence of sleep cycles for every night of monitoring. We further evaluated the effect of seizures and AEDs on trends in the RDP metric.

Results: We observed oscillations corresponding to sleep cycles in the RDP time-series. There was a significant increasing trend in our RDP sleep metric over the course of monitoring. Seizures and AEDs did not significantly affect this trend.

Conclusions: The RDP metric increased during icEEG monitoring, independent of seizures and AEDs. This increase may be due to a number of factors and these factors appear to outweigh the effects of seizures and AEDs.

Significance: Our results indicate that sleep is not uniform during icEEG monitoring, rather there is a considerable increasing, multi-night change in sleep structure.