Impact of Chronotype-Based scheduling on sleep EEG in first seizure Patients: A pilot study

Sleep EEG (S-EEG) is commonly used to increase diagnostic yield after a first suspected seizure, yet its scheduling is usually standardized and does not account for individual circadian preference. We investigated whether aligning S-EEG timing to individual chronotype improves sleep parameters and IED detection compared with standard morning recordings in a pilot prospective study.

In this prospective observational two-phase study, patients aged ≥ 18 years undergoing diagnostic work-up for a first suspected unprovoked seizure underwent S-EEG after partial sleep deprivation. In Phase I, all recordings were performed at 8:00 AM. In Phase II, recording time was adapted to chronotype assessed by the Morningness-Eveningness Questionnaire (early chronotypes at 2:00 PM, late chronotypes at 8:00 AM). Sleep architecture and IED detection were compared between phases.

Eighty-eight patients (age range 18-84 years; 60.3% male) were included. Groups were comparable in demographic and clinical variables. Total sleep time and N2 sleep were significantly longer with standard morning scheduling than with chronotype-based scheduling. IEDs were more frequent in chronotype-aligned recordings (32.6% vs. 25.0%), without a statistically significant difference (p = 0.44). The absolute difference in detection rate was 7.6% (95% CI - 11.0% to 26.4%). Neither chronotype nor sleep-related symptoms (insomnia, excessive daytime sleepiness, restless legs syndrome) were significantly associated with IED detection.

Chronotype-based scheduling of S-EEG alone did not significantly improve sleep duration or IED detection under routine clinical conditions. Sleep duration during recordings was short overall, which may have limited the ability to detect circadian effects. These findings suggest that optimization of S-EEG diagnostics may require integrated strategies beyond scheduling alone, including longer recordings or tailored sleep facilitation, rather than chronotype-based timing in isolation.